Pascal to Inch of Mercury Converter

What exactly is one pascal?

One pascal (1 Pa) = one newton of force spread over one square meter of area.

Physical interpretation:

• Place a 100-gram apple (weighing ~1 newton) flat on a table covering 1 m² (roughly 3.3 ft × 3.3 ft)
• The pressure it exerts on the table = 1 Pa
• Alternatively: 1 Pa = pressure from 10 kg spread over 1 m² (about 22 lbs on 11 sq ft)

Why it's so small: Human scale forces are typically larger and distributed over smaller areas, creating pressures in thousands or millions of pascals.

How do I convert pascals to PSI?

Formula: PSI = Pa × 0.000145038 (or Pa ÷ 6,894.76)

Step-by-step example (200,000 Pa to PSI):

1. 200,000 Pa ÷ 6,894.76 = 29.0 PSI
2. Or: 200,000 Pa × 0.000145038 = 29.0 PSI

Quick approximation:

• Convert to kPa first: 200,000 Pa = 200 kPa
• Divide by ~7: 200 kPa ÷ 7 ≈ 29 PSI (actual: 29.0 PSI)

Common conversions:

• 100,000 Pa = 100 kPa = 14.5 PSI
• 200,000 Pa = 200 kPa = 29.0 PSI (typical car tire)
• 689,476 Pa = 689 kPa = 100 PSI
• 6,894,760 Pa = 6,895 kPa = 6.89 MPa = 1,000 PSI

Pascal to PSI converter →

How many pascals in 1 PSI?

1 PSI = 6,894.76 pascals = 6.895 kPa

Examples:

• 10 PSI = 68,948 Pa = 69 kPa
• 30 PSI = 206,843 Pa = 207 kPa (car tire)
• 100 PSI = 689,476 Pa = 689 kPa (bicycle tire)
• 1,000 PSI = 6,894,760 Pa = 6.89 MPa (hydraulic system)

Memory aid: 1 PSI ≈ 7 kPa (slightly under: actual 6.895 kPa)

PSI to Pascal converter →

What is 101,325 pascals?

101,325 Pa = Standard atmospheric pressure at sea level

This is the definition of one atmosphere (1 atm), also equals:

• 101.325 kPa (easier to write/say)
• 1.01325 bar (very close to 1 bar)
• 14.696 PSI (often rounded to 14.7 PSI)
• 1,013.25 hPa or 1,013.25 mbar (meteorology)
• 760 mmHg or 760 Torr (medical/vacuum)
• 29.92 inches Hg (US weather/aviation)

Why this specific number? Historical: 1 atm was defined as average sea-level pressure supporting a 760 mm mercury column. When converted to pascals (SI units), it equals 101,325 Pa exactly.

Why use pascals if they're so small?

SI Coherence: Pascal is the fundamental SI unit—all scientific work uses it for consistency and direct traceability to base units (kg, m, s).

Universal Standard: Scientists and engineers worldwide understand pascals; international standards (ISO, IEC, IEEE) specify pressure in Pa/kPa/MPa.

Scalability with Prefixes:

• Pa (pascal): Sound, differential pressure, very low pressure
• kPa (kilopascal, ×1,000): Tires, weather, moderate engineering
• MPa (megapascal, ×1,000,000): Materials strength, hydraulics, high pressure
• GPa (gigapascal, ×1,000,000,000): Elastic modulus, extreme pressure

In practice: Nobody says "concrete strength is 30,000,000 pascals"—they say "30 MPa." The prefix system makes pascals practical across 15 orders of magnitude (from sound to diamond stiffness).

How do I convert between Pa, kPa, and MPa?

Simple decimal shifts (powers of 1,000):

Pa ↔ kPa:

• Pa → kPa: Divide by 1,000 (move decimal 3 left)
  • 250,000 Pa = 250 kPa
• kPa → Pa: Multiply by 1,000 (move decimal 3 right)
  • 220 kPa = 220,000 Pa

kPa ↔ MPa:

• kPa → MPa: Divide by 1,000
  • 5,000 kPa = 5 MPa
• MPa → kPa: Multiply by 1,000
  • 0.5 MPa = 500 kPa

Pa ↔ MPa:

• Pa → MPa: Divide by 1,000,000 (move decimal 6 left)
  • 50,000,000 Pa = 50 MPa
• MPa → Pa: Multiply by 1,000,000 (move decimal 6 right)
  • 2 MPa = 2,000,000 Pa

Quick reference:

• 1 Pa = 0.001 kPa = 0.000001 MPa
• 1 kPa = 1,000 Pa = 0.001 MPa
• 1 MPa = 1,000,000 Pa = 1,000 kPa

kPa to Pa converter → MPa to Pa converter →

What's the difference between Pa and hPa?

Pa (pascal) = 1 N/m² (base SI pressure unit)

hPa (hectopascal) = 100 Pa (hecto = ×100 prefix)

Relationship: 1 hPa = 100 Pa = 0.1 kPa

Why hPa exists:

• Meteorology uses hPa because it's numerically identical to the millibar (mbar): 1 hPa = 1 mbar
• Weather services transitioned from millibars to hectopascals during SI adoption while keeping familiar numbers
• "Pressure is 1015 hPa" = "Pressure is 1015 mbar" (same number, SI vs non-SI unit)

Conversions:

• Standard atmosphere: 101,325 Pa = 1,013.25 hPa = 101.325 kPa
• Hurricane (low): 900 hPa = 90,000 Pa = 90 kPa
• High pressure: 1,040 hPa = 104,000 Pa = 104 kPa

Usage: Always use hPa for weather/meteorology, kPa for engineering, Pa for acoustics/differentials.

How does pressure change with altitude?

Rule of thumb near sea level: Pressure drops ~1 kPa (0.15 PSI) per 80 meters (262 feet) elevation gain.

Common elevations:

• Sea level: 101.3 kPa (14.7 PSI) = 1,013 hPa
• 500 m (1,640 ft): 95.5 kPa (13.8 PSI)
• 1,000 m (3,281 ft): 90.0 kPa (13.1 PSI)—Albuquerque, NM
• 1,600 m (5,280 ft): 83.0 kPa (12.0 PSI)—Denver, CO (17% less than sea level)
• 2,000 m (6,562 ft): 79.5 kPa (11.5 PSI)—Flagstaff, AZ
• 3,000 m (9,843 ft): 70.0 kPa (10.2 PSI)—Leadville, CO
• 5,000 m (16,404 ft): 54.0 kPa (7.8 PSI)—Everest Base Camp
• 8,849 m (29,032 ft): 33.7 kPa (4.9 PSI)—Mount Everest summit (1/3 sea level)

Why it matters:

• Engine performance: 10-15% power loss at Denver vs sea level (less oxygen)
• Boiling point: Water boils at 95°C (203°F) in Denver vs 100°C (212°F) at sea level
• Breathing: Half oxygen partial pressure on Everest = extreme physiological stress
• Aircraft cabin: Pressurized to 75-80 kPa (equivalent to 2,400 m) for passenger comfort

What pressure is considered "high pressure" or "low pressure"?

Depends on context—atmospheric, hydraulic, vacuum, or materials:

Atmospheric (Weather):

• Low pressure: <1,000 hPa (100 kPa)—storms, rain, unsettled weather
• Normal pressure: 1,005-1,020 hPa (100-102 kPa)
• High pressure: >1,020 hPa (102 kPa)—clear, calm, stable weather
• Very high: >1,040 hPa (104 kPa)—extreme cold, stagnant air

Hydraulic Systems:

• Low pressure: <7 MPa (1,000 PSI)—power steering, light hydraulics
• Medium pressure: 7-20 MPa (1,000-3,000 PSI)—excavators, industrial machinery
• High pressure: 20-70 MPa (3,000-10,000 PSI)—presses, injection molding
• Ultra-high: >100 MPa (14,500 PSI)—waterjets, scientific equipment

Vacuum (Below Atmospheric):

• Low vacuum: 100-10 kPa absolute (0.1-0.9 atm)
• Medium vacuum: 10 kPa to 0.1 Pa—industrial applications
• High vacuum: 0.1 to 10⁻⁵ Pa—electronics, coating
• Ultra-high vacuum: <10⁻⁵ Pa—semiconductors, research

Material Stress:

• Low stress: <100 MPa—plastic components, low loads
• Medium stress: 100-500 MPa—structural steel, aluminum
• High stress: 500-2,000 MPa—high-strength alloys, aerospace
• Extreme stress: >2,000 MPa—cutting tools, advanced ceramics

Can I use pascals for stress and strain calculations?

Yes—pascals are the correct SI unit for stress.

Stress = Force / Area = N / m² = Pa (identical to pressure)

Key stress types (all measured in Pa/MPa):

• Tensile stress: Pulling/stretching force per area
• Compressive stress: Crushing/squashing force per area
• Shear stress: Parallel/sliding force per area
• Bending stress: Combination of tensile and compressive

Engineering convention: Always use MPa (megapascals) for material stress:

• Aluminum yield strength: 275 MPa (not 275,000,000 Pa)
• Steel tensile strength: 400 MPa
• Concrete compressive strength: 30 MPa

Strain (deformation) is dimensionless:

• Strain = ΔL / L (change in length / original length)
• Reported as ratio (0.002) or percent (0.2%)
• No units—not measured in pascals

Young's Modulus (stiffness) = Stress / Strain:

• Units: Pa or MPa or GPa (since strain is dimensionless)
• Steel: E = 200 GPa (200,000 MPa = 200,000,000,000 Pa)

How do I measure pressure in pascals?

Pressure measurement devices:

1. Mechanical Gauges:

• Bourdon tube gauge: Curved tube straightens under pressure, moves needle
• Dial gauges: Common in industry, typically read PSI or bar (convert to Pa)
• Accuracy: ±1-2% of full scale

2. Digital Pressure Transducers:

• Piezoresistive sensors: Resistance changes with pressure (semiconductors)
• Strain gauge sensors: Diaphragm deflection measured electrically
• Capacitive sensors: Pressure changes capacitance between plates
• Output: Voltage/current proportional to pressure, digitally displayed in user-selected units (Pa, kPa, PSI, bar)
• Accuracy: ±0.1% to ±0.5% full scale

3. Barometers (Atmospheric Pressure):

• Mercury barometer: Height of mercury column (760 mm = 101.325 kPa)
• Aneroid barometer: Mechanical, uses evacuated capsule that expands/contracts
• Electronic barometer: MEMS sensor (smartphones, weather stations)—reads in hPa

4. Manometers (Differential Pressure):

• U-tube manometer: Liquid column height difference (mm H₂O or mm Hg)
• Convert: 1 mm H₂O = 9.807 Pa, 1 mm Hg = 133.322 Pa
• Use: HVAC, low-pressure differentials

5. Vacuum Gauges:

• Thermocouple gauge: Gas thermal conductivity (1-10⁻³ Pa)
• Ionization gauge: Ionized gas current (10⁻³ to 10⁻⁹ Pa)
• Pirani gauge: Heated wire resistance change (10 to 10⁻² Pa)

Calibration: Reference standards traceable to national metrology institutes (NIST, PTB) maintain pressure accuracy in pascals.