Meter to Parsec Converter
Convert meters to parsecs with our free online length converter.
Quick Answer
1 Meter = 3.240756e-17 parsecs
Formula: Meter × conversion factor = Parsec
Use the calculator below for instant, accurate conversions.
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All conversion formulas on UnitsConverter.io have been verified against NIST (National Institute of Standards and Technology) guidelines and international SI standards. Our calculations are accurate to 10 decimal places for standard conversions and use arbitrary precision arithmetic for astronomical units.
Meter to Parsec Calculator
How to Use the Meter to Parsec Calculator:
- Enter the value you want to convert in the 'From' field (Meter).
- The converted value in Parsec will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Length category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Meter to Parsec: Step-by-Step Guide
Converting Meter to Parsec involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Meter = 3.2408e-17 parsecsExample Calculation:
Convert 10 meters: 10 × 3.2408e-17 = 3.2408e-16 parsecs
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
Need to convert to other length units?
View all Length conversions →What is a Meter and a Parsec?
The meter (US spelling) or metre (International spelling) (symbol: m) is the base unit of length in the International System of Units (SI). It is one of the seven SI base units and forms the foundation for measuring distance in the metric system.
Modern Definition (1983): The meter is defined as the distance traveled by light in a vacuum in exactly 1/299,792,458 of a second. This definition links the meter to the speed of light, a fundamental constant of nature (c = 299,792,458 meters per second).
Key relationships:
- 1 meter = 100 centimeters (cm)
- 1 meter = 1,000 millimeters (mm)
- 1 meter = 0.001 kilometers (km)
- 1,000 meters = 1 kilometer
In terms of imperial/US customary units:
- 1 meter ≈ 3.28084 feet (ft) - Convert m to ft
- 1 meter ≈ 39.3701 inches (in) - Convert m to inches
- 1 meter ≈ 1.09361 yards (yd) - Convert m to yards
Visual perspective (how long is it?):
- 1 meter ≈ Length of a guitar
- 1 meter ≈ Distance from nose to fingertips (arm outstretched)
- 1 meter ≈ One adult step/stride
- 1 meter ≈ Width of a single bed
- 2 meters ≈ Standard doorway height
- 5 meters ≈ Length of a small car
It is the fundamental unit upon which all other SI length units are based through decimal multiplication or division.
Convert between length units: meter converter
and Standards
Geometric Definition
The parsec is defined through trigonometric parallax:
1 parsec = the distance at which 1 astronomical unit (AU) subtends an angle of 1 arcsecond (1″)
Mathematically:
- 1 parsec = 1 AU / tan(1″)
- Since 1″ = 1/3600 degree = π/648,000 radians ≈ 4.8481 × 10⁻⁶ radians
- For small angles: tan(θ) ≈ θ (in radians)
- 1 parsec ≈ 1 AU / 4.8481 × 10⁻⁶ ≈ 206,265 AU
Exact IAU Value
The International Astronomical Union (IAU) defines the parsec exactly as:
1 parsec = 648,000/π AU ≈ 206,264.806247 AU
Using the IAU-defined astronomical unit (1 AU = 149,597,870,700 meters exactly as of 2012):
1 parsec = 30,856,775,814,913,673 meters (exactly)
Or approximately:
- 3.0857 × 10¹⁶ meters
- 30.857 trillion kilometers
- 19.174 trillion miles
Relationship to Light-Year
The light-year (distance light travels in one Julian year) relates to the parsec:
1 parsec ≈ 3.26156 light-years
More precisely: 1 pc = 3.261563777 ly (using Julian year of 365.25 days)
Standard Multiples
Kiloparsec (kpc): 1 kpc = 1,000 pc ≈ 3,262 ly
- Used for distances within galaxies
- Milky Way diameter: ~30 kpc
Megaparsec (Mpc): 1 Mpc = 1,000,000 pc ≈ 3.26 million ly
- Used for intergalactic distances
- Andromeda Galaxy: ~0.77 Mpc
Gigaparsec (Gpc): 1 Gpc = 1,000,000,000 pc ≈ 3.26 billion ly
- Used for cosmological distances
- Observable universe radius: ~14 Gpc
Note: The Meter is part of the metric (SI) system, primarily used globally in science and trade. The Parsec belongs to the imperial/US customary system.
History of the Meter and Parsec
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Pre-Revolutionary France (Pre-1790s): France used hundreds of different local length units, creating confusion in trade and science. The need for a universal, standardized system became critical.
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Birth of the Meter (1791-1793): During the French Revolution, the French Academy of Sciences proposed a new unit of length based on natural constants. They defined the meter as one ten-millionth (1/10,000,000) of the distance from the Earth's equator to the North Pole along the meridian passing through Paris.
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Meridian Survey (1792-1799): Astronomers Pierre Méchain and Jean-Baptiste Delambre conducted a seven-year expedition to measure the meridian arc from Dunkirk to Barcelona to determine the exact length of the meter. This ambitious survey became legendary in scientific history.
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Platinum Meter Bar (1799): Based on the meridian measurements, the first physical standard was created: a platinum bar stored in the French National Archives. This became the legal meter in France.
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Treaty of the Metre (1875): Seventeen nations signed this international treaty, establishing the General Conference on Weights and Measures (CGPM) and the International Bureau of Weights and Measures (BIPM) to maintain global measurement standards.
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International Prototype Meter (1889): A more precise platinum-iridium bar was created and designated as the international standard. This prototype was kept at the BIPM near Paris under controlled conditions (specific temperature, pressure, support points).
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Krypton-86 Definition (1960): To improve accuracy and reproducibility, the meter was redefined as 1,650,763.73 wavelengths of the orange-red light emitted by krypton-86 atoms in a vacuum. This was the first definition based on atomic physics rather than a physical object.
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Speed of Light Definition (1983): The current definition was adopted, fixing the speed of light at exactly 299,792,458 m/s and defining the meter based on this constant. This provided the most stable and reproducible definition possible, as the speed of light is a fundamental constant of nature.
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Global Adoption: Today, the meter is used by virtually every country in the world. Only Liberia, Myanmar, and the United States have not fully adopted the metric system for everyday use, though even the US uses it extensively in science, medicine, and manufacturing.
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Why It Matters: The meter's evolution from a physical bar to a definition based on universal constants represents humanity's quest for increasingly precise and universally accessible measurement standards.
and Evolution
Pre-Parsec Era: The Parallax Quest (1600s-1830s)
The concept of stellar parallax dates to ancient Greek astronomy, but detecting it required centuries of technological advancement.
Galileo Galilei (1610) suggested that if Earth orbits the Sun, nearby stars should show annual parallax shifts against distant background stars. No parallax was detected, leading geocentrists to argue Earth must be stationary.
James Bradley (1728) discovered stellar aberration (apparent star position shifts due to Earth's orbital motion combined with finite light speed), confirming Earth's motion but still failing to detect parallax—stars were simply too distant.
Friedrich Wilhelm Bessel achieved the first successful parallax measurement in 1838 for 61 Cygni, determining a distance of about 10.3 light-years (3.16 parsecs, though the term didn't exist yet). This triumph came using a heliometer—a split-lens telescope enabling precise angular measurements.
Thomas Henderson measured Alpha Centauri's parallax (1832-1833, published 1839), and Friedrich Struve measured Vega's (1837), establishing parallax as the fundamental distance measurement method.
Coining the Term (1913)
Herbert Hall Turner (1861-1930), British astronomer and director of Oxford University Observatory, coined "parsec" in 1913. Before this, astronomers expressed stellar distances awkwardly:
- In astronomical units (requiring numbers in the hundreds of thousands)
- In light-years (popular but not directly tied to measurement method)
- In "parallax seconds" (inverse of parallax angle, but confusing terminology)
Turner recognized that astronomers naturally thought in terms of parallax angles. For a star with parallax angle p (in arcseconds), the distance d is simply:
d (in parsecs) = 1 / p (in arcseconds)
This elegant relationship made the parsec immediately practical. A star with 0.5″ parallax is 2 parsecs away; 0.1″ parallax means 10 parsecs; 0.01″ parallax means 100 parsecs.
IAU Adoption (1922-1938)
The 1922 IAU General Assembly in Rome endorsed the parsec as the standard unit for stellar distances, though adoption wasn't immediate or universal.
The 1938 IAU General Assembly in Stockholm formally standardized the parsec definition based on the astronomical unit and arcsecond, solidifying its status.
By the 1950s, the parsec dominated professional astronomy literature, though popular science continued preferring light-years for general audiences.
Space Age Precision (1960s-Present)
Hipparcos satellite (1989-1993): European Space Agency mission measured parallaxes for 118,000 stars with milliarcsecond precision, extending reliable parsec-based distances to hundreds of parsecs.
Gaia mission (2013-present): ESA's Gaia spacecraft has revolutionized astrometry, measuring parallaxes for 1.8 billion stars with microarcsecond precision. This extends direct parsec measurements to 10,000+ parsecs (10+ kiloparsecs), mapping our galaxy's structure in unprecedented detail.
2012 IAU redefinition: The IAU redefined the astronomical unit as exactly 149,597,870,700 meters (no longer based on Earth's actual orbit, which varies slightly). This made the parsec exactly 648,000/π AU, providing a stable definition independent of Earth's orbital variations.
Common Uses and Applications: meters vs parsecs
Explore the typical applications for both Meter (metric) and Parsec (imperial/US) to understand their common contexts.
Common Uses for meters
The meter is the fundamental length unit used across virtually all fields worldwide:
Science and Research
The universal standard in all scientific disciplines. Essential for maintaining consistency in international research and allowing scientists globally to share and compare results.
Scientific Applications:
- Physics experiments and calculations
- Chemistry lab measurements
- Biology specimen measurements
- Astronomy (often combined with larger units like megameters or astronomical units)
- Geology and earth sciences
- Medical research and diagnostics
Why meters in science:
- SI base unit ensures universal understanding
- Decimal system simplifies calculations
- Precise definition based on fundamental constants
- Required for publication in scientific journals
- Enables international collaboration
Convert for scientific work: meters to other units
Construction and Engineering
Standard unit for building plans, specifications, and measurements in most countries. Essential for architectural drawings, structural engineering, and construction site work.
Construction uses:
- Building dimensions and floor plans
- Material specifications (lumber, pipes, cables)
- Site surveying and land measurements
- Road and bridge design
- Utility installations
- Safety clearances and regulations
Engineering disciplines:
- Civil engineering (infrastructure, roads, dams)
- Mechanical engineering (machine design, tolerances)
- Electrical engineering (cable runs, installations)
- Structural engineering (building analysis)
Why meters dominate:
- International building codes
- Global supply chains use metric
- Simplified scaling (1:100, 1:50 drawings)
- Easy conversion between units (mm, cm, m, km)
Athletics and Sports
The standard for track and field events, swimming pools, and most international sports. Creates consistency in competition and record-keeping worldwide.
Track and Field:
- All race distances (100m, 200m, 400m, etc.)
- Field event measurements (high jump, long jump, javelin)
- Track dimensions (400m oval)
Swimming:
- Pool lengths (25m, 50m)
- Race distances
- Pool depth specifications
Other Sports:
- Soccer field dimensions
- Basketball court measurements (FIBA)
- Tennis court specifications
- Ski jump distances
World Records: All Olympic and international records use meters
Manufacturing and Industry
Essential for product design, quality control, and manufacturing specifications. Enables global supply chains and standardized parts.
Manufacturing uses:
- Product dimensions and tolerances
- Machine specifications
- Assembly line measurements
- Quality control standards
- Shipping container sizes
- Material cutting and fabrication
Industries:
- Automotive (car dimensions, parts)
- Aerospace (aircraft specifications)
- Electronics (component spacing)
- Textiles (fabric measurements)
- Furniture (product dimensions)
Everyday Life (Metric Countries)
Daily measurements for height, distance, and dimensions in 95% of the world's countries.
Personal measurements:
- Human height and weight
- Clothing sizes (combined with cm)
- Recipe distances (rare, but when needed)
- Home improvement projects
Shopping:
- Fabric by the meter
- Carpeting and flooring
- Curtains and blinds
- Garden hoses and cables
Driving:
- Road signs (distances in km, using meters as base)
- Vehicle dimensions
- Parking regulations
Use our meter converter for everyday conversions.
Aviation and Maritime
Critical for navigation, altitude, and safety specifications in international travel.
Aviation:
- Runway lengths
- Aircraft dimensions
- Altitude (often in feet, but meters in some regions)
- Visibility distances
Maritime:
- Ship dimensions
- Harbor depths (often in meters or fathoms)
- Vessel clearances
- Navigation distances
Medical and Healthcare
Standard for patient measurements and medical equipment in most healthcare systems worldwide.
Medical uses:
- Patient height
- Wound measurements
- Medical imaging distances
- Equipment specifications
- Hospital room dimensions
- Surgical instrument lengths
When to Use parsecs
Stellar Astronomy and Parallax Measurements
The parsec's primary use is measuring stellar distances via trigonometric parallax:
Parallax formula: d (parsecs) = 1 / p (arcseconds)
Ground-based observatories: Measure parallaxes to ~0.01″ accuracy, reliable to ~100 pc
Hipparcos satellite: Measured parallaxes to ~0.001″ (1 milliarcsecond), reliable to ~1,000 pc (1 kpc)
Gaia spacecraft: Measures parallaxes to ~0.00001″ (10 microarcseconds) for bright stars, reliable to ~10 kpc for many stars
Applications:
- Calibrating the cosmic distance ladder (using Cepheid variables, RR Lyrae stars)
- Determining absolute magnitudes of stars
- Studying stellar populations and galactic structure
- Measuring proper motions and space velocities
Galactic Structure and Dynamics
Kiloparsecs (kpc) describe structures within galaxies:
Milky Way structure:
- Galactic center (Sagittarius A*): 8.2 kpc from Sun
- Galactic disk radius: ~15 kpc
- Central bulge: ~1.5 kpc radius
- Spiral arms: trace patterns 10-15 kpc in radius
- Dark matter halo: extends to ~60 kpc
Rotation curves: Plot orbital velocity vs. distance (in kpc) from galactic center, revealing dark matter
Star formation regions: Giant molecular clouds span 10-100 pc
Globular clusters: Orbit 10-60 kpc from galactic center
Extragalactic Astronomy
Megaparsecs (Mpc) measure distances between galaxies:
Galaxy surveys: Map millions of galaxies to distances of 1,000+ Mpc, revealing large-scale structure (walls, filaments, voids)
Tully-Fisher relation: Links galaxy rotation speed to luminosity, enabling distance estimates in Mpc
Type Ia supernovae: Standard candles for measuring distances to 1,000+ Mpc
Galaxy clusters: Typical separation between major clusters ~10-50 Mpc
Superclusters: Structures spanning 100-200 Mpc (like Laniakea Supercluster containing Milky Way)
Cosmology and Universe Expansion
Megaparsecs and gigaparsecs describe cosmological distances:
Hubble constant (H₀): Measured in km/s per Mpc—describes universe expansion rate
- Current value: H₀ ≈ 67-73 (km/s)/Mpc (tension between measurement methods)
- Interpretation: Galaxy 1 Mpc away recedes at ~70 km/s; 100 Mpc away recedes at ~7,000 km/s
Hubble's Law: v = H₀ × d (where d is in Mpc, v is recession velocity)
Comoving distance: Cosmological distance accounting for universe expansion, measured in Mpc or Gpc
Redshift surveys: Map galaxy distribution to 1,000+ Mpc (z ~ 0.1-0.3 redshift)
Baryon acoustic oscillations: ~150 Mpc characteristic scale in galaxy distribution, used as "standard ruler"
Astrophysical Research Papers
Parsecs are the default distance unit in professional astronomy journals:
Observational papers: Report star/galaxy distances in pc, kpc, or Mpc
Theoretical models: Express scale lengths in parsecs (e.g., "disk scale length of 3 kpc")
Computer simulations: Use parsec-based units (or comoving kpc/Mpc for cosmological sims)
Standard convention: Professional astronomers think and calculate in parsecs, converting to light-years only for public communication
Additional Unit Information
About Meter (m)
How long is a meter visually?
One meter is about the distance from your nose to your fingertips when you extend your arm straight out to the side.
Visual comparisons:
- Slightly longer than a yard (1 m = 1.09 yards)
- About 3.3 feet (one adult stride)
- Length of a guitar (most acoustic guitars)
- Width of a single bed
- Slightly longer than a baseball bat
- Three average-sized rulers (30cm each)
Body measurements:
- Most adults can approximate 1 meter with arm span from nose to fingertips
- One large step/stride for most adults
- Height from ground to waist/hip for average adult
Common objects exactly 1 meter:
- Meter stick/ruler (by definition)
- Certain guitar models
- Standard yoga mat width (60cm) is just over half a meter
To remember: Think of it as "just over 3 feet" or "slightly longer than a yard"
How many feet are in a meter?
One meter equals approximately 3.28084 feet, commonly rounded to 3.28 feet.
Exact conversion: 1 meter = 3.280839895 feet
Practical conversions:
- 1 meter ≈ 3.28 feet
- 2 meters ≈ 6.56 feet
- 5 meters ≈ 16.4 feet
- 10 meters ≈ 32.8 feet
- 100 meters ≈ 328 feet
Reverse conversion (feet to meters):
- 1 foot = 0.3048 meters (exactly)
- 3 feet ≈ 0.91 meters
- 6 feet ≈ 1.83 meters
- 10 feet ≈ 3.05 meters
Why 3.28?
- Based on the international foot definition (0.3048 m)
- 1 meter ÷ 0.3048 meters/foot = 3.28084 feet
Quick estimation: Multiply meters by 3 for a rough approximation (though this underestimates by ~9%)
Use our meter to feet converter for accurate conversions.
How many centimeters are in a meter?
There are exactly 100 centimeters (cm) in one meter.
Why 100?: The prefix "centi-" means 1/100, so a centimeter is 1/100 of a meter.
Conversion:
- 1 meter = 100 centimeters
- To convert meters to cm: multiply by 100
- To convert cm to meters: divide by 100
Examples:
- 0.5 meters = 50 cm
- 1.5 meters = 150 cm
- 2.75 meters = 275 cm
- 50 cm = 0.5 meters
- 175 cm = 1.75 meters (typical adult height)
Remember: Move the decimal point two places:
- Meters → cm: Move right (1.5 m = 150 cm)
- Cm → meters: Move left (150 cm = 1.5 m)
Use our meter to cm converter for instant conversions.
Is the meter used in the United States?
Officially: The US uses the metric system in science, medicine, military, and many industries, but the US customary system (feet, inches, miles) dominates everyday life.
Where meters ARE used in the US:
- Science and research: All scientific work
- Medicine: Patient measurements, medical devices
- Military: NATO standardization requires metric
- Manufacturing: Especially for export products
- Athletics: Track and field events
- Pharmaceuticals: Drug measurements
- Automotive: Many car specifications
- Electronics: Component specifications
Where meters are NOT commonly used:
- Road signs (miles, not kilometers)
- Construction (feet, inches)
- Everyday conversation (height, distance)
- Cooking (cups, ounces, not liters/grams)
- Real estate (square feet, acres)
- Weather (Fahrenheit, not Celsius)
Status: The US is officially metric (Metric Conversion Act of 1975) but implementation is voluntary, so dual systems coexist.
Fun fact: US money is metric (100 cents = 1 dollar), but most Americans don't think of it that way!
How many meters are in a kilometer?
There are exactly 1,000 meters in one kilometer.
Why: "Kilo-" is a Greek prefix meaning 1,000.
Conversion:
- 1 kilometer (km) = 1,000 meters (m)
- To convert km to m: multiply by 1,000
- To convert m to km: divide by 1,000
Examples:
- 0.5 km = 500 meters
- 1.5 km = 1,500 meters
- 2.5 km = 2,500 meters
- 5 km = 5,000 meters
- 10 km = 10,000 meters
- 500 m = 0.5 km
- 2,000 m = 2 km
Perspective:
- A kilometer is a common walking distance (10-15 minutes)
- 5K race = 5 kilometers = 5,000 meters
- Marathon = 42.195 kilometers = 42,195 meters
Remember: Move the decimal point three places:
- Km → m: Move right (1.5 km = 1,500 m)
- M → km: Move left (1,500 m = 1.5 km)
Convert: meters to kilometers | kilometers to meters
How is the meter defined today?
Current Definition (since 1983): The meter is defined as the distance light travels in a vacuum in exactly 1/299,792,458 of a second.
Why this definition?:
- Universal constant: The speed of light (c) is the same everywhere in the universe
- Extremely precise: Can be reproduced in any properly equipped laboratory
- No physical artifact: Doesn't depend on a prototype bar that could degrade
- Fundamentally stable: Based on physics, not human-made objects
What this means:
- The speed of light is fixed at exactly 299,792,458 meters per second
- This definition links length to time (which is measured even more precisely)
- Any lab with an atomic clock can reproduce the meter
Historical evolution:
- 1793: Earth meridian (1/10,000,000 of equator to pole)
- 1889: Platinum-iridium bar in Paris
- 1960: Krypton-86 wavelengths
- 1983: Speed of light (current definition)
Why it matters: This makes the meter one of the most precisely defined and reproducible units in all of science.
What's the difference between meter and metre?
No difference - they are the same unit, just different spellings!
Spelling variations:
- Meter: American English spelling (US, Philippines)
- Metre: International English spelling (UK, Canada, Australia, most other English-speaking countries)
Symbol: Both use m as the abbreviation
In practice:
- Scientific papers: Usually "metre" (international standard)
- US publications: Usually "meter"
- International Bureau (BIPM): Uses "metre"
- Both are 100% correct
Other metric units with dual spellings:
- Liter / Litre
- Centimeter / Centimetre
- Kilometer / Kilometre
Remember: The spelling doesn't affect the measurement - 1 meter = 1 metre = 1 m
How do you convert meters to inches?
To convert meters to inches, multiply by approximately 39.3701.
Conversion formula: inches = meters × 39.3701
Examples:
- 1 meter = 39.37 inches
- 2 meters = 78.74 inches
- 5 meters = 196.85 inches
- 0.5 meters = 19.69 inches
- 1.5 meters = 59.06 inches
Reverse conversion (inches to meters):
- 1 inch = 0.0254 meters (exactly)
- 12 inches (1 foot) = 0.3048 meters
- 36 inches (1 yard) = 0.9144 meters
Why 39.37?
- 1 meter = 100 cm
- 1 inch = 2.54 cm (exactly)
- 100 cm ÷ 2.54 cm/inch = 39.37 inches
Quick mental math:
- 1 meter ≈ 40 inches (close enough for rough estimates)
- 2.5 cm ≈ 1 inch, so 100 cm ≈ 40 inches
Use our meter to inches converter for precise conversions.
What is 2 meters in feet and inches?
2 meters = 6 feet 6.74 inches (or approximately 6 feet 7 inches)
Calculation:
- 2 meters = 6.56168 feet
- 6 full feet = 6 feet
- 0.56168 feet × 12 inches/foot = 6.74 inches
- Result: 6 feet 6.74 inches ≈ 6' 7"
Common 2-meter comparisons:
- Standard doorway height: 2-2.1 meters (6'7" - 6'11")
- Tall person height: 2 meters is very tall (99th percentile)
- Basketball player: Many NBA players are around 2 meters
- High jump bar: Elite athletes clear around 2 meters
Rounded conversions:
- 2.0 m = 6' 7"
- 2.1 m = 6' 11"
- 2.2 m = 7' 3"
Quick reference:
- 1.5 m = 4' 11"
- 1.8 m = 5' 11" (average adult male height)
- 2.0 m = 6' 7"
- 2.5 m = 8' 2"
Convert any height: meters to feet and inches
How many meters is a football field?
American Football:
- Playing field: 100 yards = 91.44 meters
- With end zones: 120 yards = 109.73 meters
- Width: 53.33 yards = 48.76 meters
Soccer/Football (International):
- Length: 100-110 meters (typical), 90-120 meters (FIFA rules)
- Width: 64-75 meters (typical), 45-90 meters (FIFA rules)
- Standard pitch: 105 × 68 meters
Common comparisons:
- 100 meters ≈ 1 American football field (length only, not counting end zones)
- 100 meters = 109.4 yards (9.4 yards longer than American football field)
- "100-meter dash" ≈ Length of American football field + 9 yards
Useful reference: "100 meters" is a standard way to visualize distance - slightly longer than an American football field.
Why is the meter important?
The meter is the foundation of the metric system, used by 95% of the world's population and essential for global science, trade, and communication.
Scientific importance:
- Base unit of SI system (international standard)
- Defined by fundamental constant (speed of light)
- Essential for all scientific research
- Enables global collaboration
Practical importance:
- Universal measurement standard
- Simplifies international trade
- Decimal-based (easy calculations)
- Used in manufacturing, construction, medicine
Global standardization:
- Ensures products fit across borders
- Aircraft, ships, vehicles have standard dimensions
- Medical equipment is universally compatible
- Scientific data can be shared internationally
Historical significance:
- Represents the Enlightenment ideal of universal standards
- First measurement based on nature (Earth meridian)
- Now based on fundamental physics (speed of light)
- Symbol of international cooperation
Modern life:
- GPS and navigation systems
- International sports records
- Global supply chains
- Scientific advancement
Bottom line: The meter makes global communication, commerce, and science possible.
About Parsec (pc)
What does "parsec" stand for?
Parsec is a portmanteau of "parallax of one arcsecond."
It represents the distance at which Earth's orbital radius (1 AU) subtends an angle of exactly one arcsecond (1/3600 of a degree). British astronomer Herbert Hall Turner coined the term in 1913 to provide a convenient unit directly tied to the parallax measurement method.
How is a parsec measured?
Parsecs are measured using trigonometric parallax:
- Observe a nearby star from Earth when Earth is on one side of its orbit
- Observe the same star six months later when Earth is on the opposite side
- Measure the apparent shift in the star's position against distant background stars
- Half this shift is the parallax angle p (in arcseconds)
- Calculate distance: d = 1/p parsecs
Modern method: Space telescopes like Gaia measure parallax angles with microarcsecond precision, enabling distance measurements to thousands of parsecs.
Is a parsec bigger than a light-year?
Yes, one parsec is significantly larger:
1 parsec ≈ 3.26 light-years
More precisely: 1 pc = 3.261563777 ly
Example: Proxima Centauri at 1.3 parsecs equals 4.24 light-years away.
Why the difference matters: Confusing parsecs with light-years introduces 3× error in distances.
Why do astronomers prefer parsecs over light-years?
Astronomers prefer parsecs for several reasons:
1. Direct observational connection: Parallax angle p (arcseconds) directly gives distance d = 1/p (parsecs). No complicated conversion needed.
2. Professional standard: IAU endorsed parsecs in 1922; they're now universal in research papers and textbooks.
3. Convenient multiples: Kiloparsecs (kpc) for galactic distances, megaparsecs (Mpc) for cosmological distances provide natural scales.
4. Hubble constant units: Universe expansion rate naturally expressed in (km/s)/Mpc.
5. Definition stability: Light-year depends on year length definition (tropical, Julian, sidereal); parsec defined purely by geometry.
Light-years remain popular in public communication because "year" is familiar, while "parallax arcsecond" requires technical knowledge.
How many astronomical units are in a parsec?
1 parsec = 206,265 astronomical units (AU) (approximately)
More precisely: 1 pc = 206,264.806247 AU
This number arises from: 1 pc = 1 AU / tan(1″), and since 1″ = π/648,000 radians:
- 1 pc = 1 AU / (π/648,000) = 648,000/π AU ≈ 206,265 AU
Context: Since 1 AU ≈ 150 million km (Earth-Sun distance), 1 parsec ≈ 31 trillion km.
What is a kiloparsec and megaparsec?
Kiloparsec (kpc): 1 kpc = 1,000 parsecs ≈ 3,262 light-years
- Used for: Galactic-scale distances
- Examples: Sun to Milky Way center (8 kpc), galaxy diameters (10-50 kpc)
Megaparsec (Mpc): 1 Mpc = 1,000,000 parsecs ≈ 3.26 million light-years
- Used for: Intergalactic distances, cosmology
- Examples: Andromeda Galaxy (0.77 Mpc), Virgo Cluster (16.5 Mpc), Hubble constant measured in (km/s)/Mpc
Gigaparsec (Gpc): 1 Gpc = 1,000,000,000 parsecs ≈ 3.26 billion light-years
- Used for: Large-scale cosmological structures
- Example: Observable universe radius (~14 Gpc)
Is the parsec an SI unit?
No, the parsec is not an SI unit. The SI unit of length is the meter (m).
However, the parsec is:
- Recognized by the IAU (International Astronomical Union)
- Accepted for use with SI in astronomy contexts
- Defined exactly in terms of the AU (which is defined exactly in meters)
Why not SI?: The parsec arose naturally from astronomical practice and remains far more practical than expressing stellar distances in meters (which would require numbers like 10¹⁶ to 10²³).
Analogy: Like the electronvolt (eV) in particle physics, the parsec is a specialized unit indispensable to its field despite not being SI.
How far can parallax measure distances?
Ground-based telescopes: ~0.01 arcsecond precision → reliable to ~100 parsecs
Hubble Space Telescope: ~0.001 arcsecond (1 milliarcsecond) → reliable to ~1,000 parsecs (1 kpc)
Hipparcos satellite (1989-1993): ~0.001 arcsecond → 118,000 stars measured to 100-1,000 pc
Gaia spacecraft (2013-present): ~0.00001 arcsecond (10 microarcseconds) for bright stars → reliable to ~10,000 parsecs (10 kpc)
- Measured 1.8 billion stars
- Revolutionary precision enables mapping entire Milky Way disk
Fundamental limit: Stars beyond 10-20 kpc have unmeasurably small parallaxes with current technology. For greater distances, astronomers use indirect methods (Cepheids, Type Ia supernovae, redshift).
Did Han Solo make the Kessel Run in "less than 12 parsecs"?
Famous Star Wars quote: "She made the Kessel Run in less than twelve parsecs."
The issue: Parsec measures distance, not time. Saying "less than 12 parsecs" for a speed achievement is like saying "I drove to work in less than 5 miles."
Fan explanations (retroactive justifications):
- The Kessel Run involves navigating near black holes; a shorter distance means a more dangerous, direct route
- Skilled pilots can shave distance by flying closer to gravitational hazards
- This reinterprets "12 parsecs" as boasting about route optimization, not speed
Real answer: George Lucas likely confused parsecs with a time unit when writing the script. The line became famous enough that later writers invented explanations making it technically correct.
Takeaway: In real astronomy, parsecs always measure distance, never time.
How do parsecs relate to the Hubble constant?
The Hubble constant (H₀) describes universe expansion and is typically expressed as:
H₀ ≈ 70 (km/s)/Mpc
Interpretation: For every megaparsec of distance, recession velocity increases by ~70 km/s.
Examples using Hubble's Law (v = H₀ × d):
- Galaxy 1 Mpc away: recedes at ~70 km/s
- Galaxy 10 Mpc away: recedes at ~700 km/s
- Galaxy 100 Mpc away: recedes at ~7,000 km/s
- Galaxy 1,000 Mpc away: recedes at ~70,000 km/s
Hubble length: c/H₀ ≈ 4,400 Mpc (14.4 billion ly) - characteristic distance scale of observable universe
Why Mpc?: Using megaparsecs keeps Hubble constant values convenient (70 rather than 0.000000000070 if using parsecs, or 2.3 × 10⁻¹⁸ if using SI meters).
What's the farthest distance ever measured in parsecs?
Observable universe radius: ~14,000 Mpc = 14 Gpc (46 billion light-years comoving distance)
Most distant galaxy observed (as of 2023): JADES-GS-z13-0 at redshift z ≈ 13.2
- Comoving distance: ~4,200 Mpc (13.7 billion light-years light-travel distance)
- Due to universe expansion, it's now ~10,000 Mpc (32 billion light-years) away
Cosmic microwave background: Emitted 380,000 years after Big Bang
- Comoving distance to CMB surface: ~14,000 Mpc (46 billion light-years)
Beyond measurement: The observable universe has a finite size (~14 Gpc radius) due to finite age and light speed. Objects beyond this "cosmological horizon" are unobservable because their light hasn't reached us yet.
Conversion Table: Meter to Parsec
| Meter (m) | Parsec (pc) |
|---|---|
| 0.5 | 0 |
| 1 | 0 |
| 1.5 | 0 |
| 2 | 0 |
| 5 | 0 |
| 10 | 0 |
| 25 | 0 |
| 50 | 0 |
| 100 | 0 |
| 250 | 0 |
| 500 | 0 |
| 1,000 | 0 |
People Also Ask
How do I convert Meter to Parsec?
To convert Meter to Parsec, enter the value in Meter in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our length converter page to convert between other units in this category.
Learn more →What is the conversion factor from Meter to Parsec?
The conversion factor depends on the specific relationship between Meter and Parsec. You can find the exact conversion formula and factor on this page. Our calculator handles all calculations automatically. See the conversion table above for common values.
Can I convert Parsec back to Meter?
Yes! You can easily convert Parsec back to Meter by using the swap button (⇌) in the calculator above, or by visiting our Parsec to Meter converter page. You can also explore other length conversions on our category page.
Learn more →What are common uses for Meter and Parsec?
Meter and Parsec are both standard units used in length measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our length converter for more conversion options.
For more length conversion questions, visit our FAQ page or explore our conversion guides.
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Last verified: December 3, 2025