Pound per Square Inch to Torr Converter
Convert pounds per square inch to torr with our free online pressure converter.
Quick Answer
1 Pound per Square Inch = 51.714933 torr
Formula: Pound per Square Inch × conversion factor = Torr
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.
Pound per Square Inch to Torr Calculator
How to Use the Pound per Square Inch to Torr Calculator:
- Enter the value you want to convert in the 'From' field (Pound per Square Inch).
- The converted value in Torr will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Pressure category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Pound per Square Inch to Torr: Step-by-Step Guide
Converting Pound per Square Inch to Torr involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
Torr = psi × 51.7149Example Calculation:
1 psi = 51.714933 Torr
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 pressure units?
View all Pressure conversions →What is a Pound per Square Inch and a Torr?
PSI (pounds per square inch) is a unit of pressure expressing force in pounds-force distributed over an area of one square inch. One PSI equals approximately 6,894.76 Pascals or 0.0689 bar.
Key conversions:
- 1 PSI = 6,894.76 Pa (Pascals)
- 1 PSI = 6.895 kPa (Kilopascals)
- 1 PSI = 0.0689 bar
- 14.7 PSI = 1 atmosphere (atm)
- Convert instantly with our PSI to bar converter
Important distinction:
- PSIG (gauge pressure): Relative to atmospheric pressure (0 PSIG = atmospheric)
- PSIA (absolute pressure): Relative to perfect vacuum
- Most pressure gauges show PSIG
The Torr (symbol: Torr) is a unit of pressure based on an absolute scale. It is not an SI unit, but it is widely used in science and engineering.
The Modern Definition: 1 Torr is defined as exactly 1/760 of a standard atmosphere (1 atm).
Since a standard atmosphere is defined as exactly 101,325 Pascals (Pa), the exact value of one Torr is: 1 Torr = 101,325 / 760 Pascals ≈ 133.322368421 Pascals.
** Torr vs. mmHg**: Historically, the Torr was intended to be same as the millimeter of mercury (mmHg). However, because the density of mercury changes with temperature and local gravity varies across the Earth, the mmHg is not a "true" absolute unit. To solve this, the Torr was redefined as a fixed fraction of an atmosphere, making it a perfectly stable unit regardless of where or the temperature at which you measure it.
Key standard relationships:
- 1 Torr = 1,000 milliTorr (mTorr)
- 760 Torr = 1 standard atmosphere (atm)
- 1 Torr ≈ 1.333 millibars (mbar)
- 1 Torr ≈ 0.0193 PSI (pounds per square inch)
Note: The Pound per Square Inch is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Torr belongs to the imperial/US customary system.
History of the Pound per Square Inch and Torr
: From the First Barometer to Modern Vacuums
The history of the Torr is the history of our understanding of the "void" and the air around us.
1. Evangelista Torricelli and the "Sea of Air" (1643)
Before the 1640s, scientists believed that "nature abhors a vacuum" and that space was always filled with something. Evangelista Torricelli, a student of Galileo, challenged this. He filled a glass tube with mercury and inverted it into a bowl. Instead of all the mercury flowing out, it stopped at a height of about 76 cm (760 mm).
Torricelli correctly deduced that it wasn't a "pull" from the vacuum at the top of the tube, but the weight of the atmosphere pushing down on the mercury in the bowl that held the liquid up. He famously stated: "We live submerged at the bottom of an ocean of elementary air."
2. The Birth of the Name (1913)
For centuries, pressure was simply measured in "inches of mercury" or "millimeters of mercury." In 1913, the unit was formally named the Torr to honor Torricelli.
3. The Great Redefinition (1954)
As science became more precise, the variance in mercury density became a problem (a "millimeter of mercury" in the Arctic was technically different from one at the Equator). In 1954, at the 10th General Conference on Weights and Measures, the Standard Atmosphere was fixed at exactly 101,325 Pascals. Consequently, the Torr was redefined as exactly 1/760 of that value, decoupling it from the physical properties of mercury forever.
Common Uses and Applications: pounds per square inch vs torr
Explore the typical applications for both Pound per Square Inch (imperial/US) and Torr (imperial/US) to understand their common contexts.
Common Uses for pounds per square inch
Automotive Industry
Primary pressure unit for tire inflation, fuel injection systems, turbo boost pressure, brake systems, and hydraulic lifts throughout North America.
Manufacturing & Industry
Standard for hydraulic presses, pneumatic systems, compressors, pressure vessels, and industrial equipment specifications in the US.
Construction
Used for concrete pumps, hydraulic tools, pneumatic nailing equipment, sandblasting, and compressed air systems.
HVAC & Refrigeration
Universal unit for refrigerant pressures, duct static pressure, gas line pressure, and system diagnostics in US HVAC industry.
Plumbing
Standard for water pressure measurements, pressure regulators, well pumps, and municipal water systems in the United States.
When to Use torr
Additional Unit Information
About Pound per Square Inch (psi)
What is a good PSI for car tires?
Standard car tire pressure: 32-35 PSI (when cold)
Always check your specific vehicle:
- Driver's door jamb sticker (most reliable)
- Owner's manual
- Fuel filler door (some vehicles)
By vehicle type:
- Compact cars: 30-33 PSI
- Sedans: 32-35 PSI
- SUVs/Light trucks: 35-45 PSI
- High-performance: 36-40 PSI
Important: Check when tires are COLD (before driving). Tire pressure increases 4-6 PSI after driving.
Convert to your region: PSI to Bar →
How do I convert PSI to bar?
Formula: Bar = PSI × 0.0689476 (or divide PSI by 14.5)
Examples:
- 10 PSI = 0.69 bar
- 30 PSI = 2.07 bar
- 50 PSI = 3.45 bar
- 100 PSI = 6.89 bar
Quick mental math: Divide PSI by 14.5 or 15
- 30 PSI ÷ 15 ≈ 2 bar (actual: 2.07)
Use our PSI to Bar converter →
What does PSIG vs PSIA mean?
PSIG (Pounds per Square Inch Gauge):
- Pressure relative to atmospheric pressure
- 0 PSIG = atmospheric pressure (14.7 PSIA at sea level)
- What most pressure gauges show
- Used for tires, compressors, hydraulics
PSIA (Pounds per Square Inch Absolute):
- Pressure relative to perfect vacuum
- 0 PSIA = absolute vacuum
- 14.7 PSIA = atmospheric pressure at sea level
- Used in scientific/engineering calculations
Conversion: PSIA = PSIG + 14.7 (at sea level)
Example: 32 PSIG tire pressure = 46.7 PSIA total pressure
What is 100 PSI in bar and kPa?
100 PSI equals:
- 6.89 bar
- 689.5 kPa (kilopascals)
- 0.689 MPa (megapascals)
Quick conversions:
Context: 100 PSI is typical for:
- Heavy-duty air compressor output
- Semi-truck tire pressure
- Pneumatic tool operating pressure
Is 40 PSI good tire pressure?
40 PSI can be correct depending on your vehicle:
Good for:
- Large SUVs and trucks
- Some high-performance vehicles
- Vehicles when fully loaded
Too high for:
- Most passenger cars (typically 32-35 PSI)
- Compact cars (typically 30-33 PSI)
How to know:
- Check driver's door jamb sticker
- Consult owner's manual
- Never rely on tire sidewall (that's MAX pressure)
Effects of overinflation:
- Harsher ride
- Reduced traction
- Uneven tire wear (center wears faster)
Always check: When tires are COLD, before driving.
How many PSI in 1 atmosphere?
1 atmosphere (atm) = 14.6959 PSI (approximately 14.7 PSI)
Standard atmospheric pressure at sea level:
- 14.696 PSI (PSIA)
- 101.325 kPa
- 1.01325 bar
- 760 mmHg / 760 Torr
- 29.92 inHg
Altitude effects:
- Sea level: 14.7 PSI
- Denver (5,280 ft): ~12.1 PSI
- 10,000 ft: ~10.1 PSI
What PSI should I set my air compressor to?
Typical settings:
General Shop Use: 90-100 PSI
- Most pneumatic tools operate best at 90 PSI
- Allows for pressure drop in hoses
Specific Applications:
- Impact wrench: 90 PSI
- Nail gun: 70-120 PSI (tool dependent)
- Paint sprayer: 25-50 PSI
- Tire inflation: 30-40 PSI
- Sandblasting: 80-100 PSI
- Air brush: 15-30 PSI
Compressor tank pressure: 125-150 PSI (maximum)
- Compressor cuts off at max (e.g., 135 PSI)
- Compressor cuts on when drops (e.g., 100 PSI)
- Set regulator to desired tool pressure (e.g., 90 PSI)
Pro tip: Set higher tank pressure, use regulator for precise tool pressure.
Why is PSI used instead of bar in the US?
Historical reasons:
- Imperial system was established before metric
- US industry standardized on PSI in early 1900s
- Extensive infrastructure built around imperial units
Practical resistance to change:
- All existing gauges, equipment use PSI
- Workforce trained in PSI
- Replacement costs would be enormous
- Cultural familiarity
Current situation:
- US is primary country still using PSI
- Scientific/international work uses metric (bar, kPa)
- Some US industries use both systems
For travelers: Most modern tire gauges show both PSI and bar.
About Torr (Torr)
What is the difference between Torr and mmHg?
For almost all practical, medical, and industrial purposes, they are the same. However, scientifically:
- Torr is defined as exactly 1/760 of a Standard Atmosphere (Standardized in 1954).
- mmHg (millimeter of mercury) is based on the actual weight of liquid mercury, which changes slightly depending on gravity and temperature.
- The difference is 1 part in 7 million. Unless you are building a particle accelerator, you can treat them as identical.
Why is Torr used in vacuum technology?
Torr is the preferred unit because most vacuum systems are based on pumping down from atmospheric pressure. Since 760 Torr is a standard atmosphere, it's very easy for an engineer to know how "far" they have to go. It also uses a logarithmic scale naturally, making it easy to talk about 10⁻⁶ or 10⁻⁹ Torr levels.
Is a Torr a "Metric" unit?
No. The official SI unit for pressure is the Pascal (Pa). However, because 1 Pascal is such a small amount of pressure (about the weight of a dollar bill on a table), scientists in specific fields prefer the Torr for convenience.
How do you convert Torr to PSI?
Multiply your Torr value by 0.0193368. Formula: PSI = Torr × 0.0193368 Example: 100 Torr ≈ 1.93 PSI.
What is a "milliTorr" (mTorr)?
Also known as a Micron, a milliTorr is 1/1,000th of a Torr. It is commonly used in "roughing" vacuum pumps (like the one in your school's physics lab or a high-end food sealer).
Is 0 Torr possible?
A "perfect" vacuum (exactly 0 Torr) is theoretically impossible according to quantum mechanics. Even in deep intergalactic space, there is a pressure of about 10⁻¹⁷ Torr due to a few stray hydrogen atoms and cosmic radiation.
Is Torr used in the medical field?
Yes, but doctors almost always call it mmHg. When a nurse says your blood pressure is "120 over 80," they are literally saying "120 Torr systolic and 80 Torr diastolic."
Who is the unit Torr named after?
It is named after Evangelista Torricelli, the Italian physicist who proved that air has weight and invented the mercury barometer in 1643.
How many Pascals are in a Torr?
Exactly 133.322368... Pascals. For most calculations, using 133.3 is sufficient.
What happens if you are exposed to 0 Torr?
This is "space vacuum." Contrary to movies, your head doesn't explode. However, the oxygen in your blood would diffuse out of your lungs into the vacuum, causing you to lose consciousness in about 15 seconds. Your skin is tough enough to hold "you" together, but you would swell up significantly as water in your tissues starts to turn to gas.
Conversion Table: Pound per Square Inch to Torr
| Pound per Square Inch (psi) | Torr (Torr) |
|---|---|
| 0.5 | 25.858 |
| 1 | 51.715 |
| 1.5 | 77.572 |
| 2 | 103.43 |
| 5 | 258.575 |
| 10 | 517.149 |
| 25 | 1,292.873 |
| 50 | 2,585.747 |
| 100 | 5,171.493 |
| 250 | 12,928.733 |
| 500 | 25,857.466 |
| 1,000 | 51,714.933 |
People Also Ask
How do I convert Pound per Square Inch to Torr?
To convert Pound per Square Inch to Torr, enter the value in Pound per Square Inch in the calculator above. The conversion will happen automatically. Use our free online converter for instant and accurate results. You can also visit our pressure converter page to convert between other units in this category.
Learn more →What is the conversion factor from Pound per Square Inch to Torr?
The conversion factor depends on the specific relationship between Pound per Square Inch and Torr. 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 Torr back to Pound per Square Inch?
Yes! You can easily convert Torr back to Pound per Square Inch by using the swap button (⇌) in the calculator above, or by visiting our Torr to Pound per Square Inch converter page. You can also explore other pressure conversions on our category page.
Learn more →What are common uses for Pound per Square Inch and Torr?
Pound per Square Inch and Torr are both standard units used in pressure measurements. They are commonly used in various applications including engineering, construction, cooking, and scientific research. Browse our pressure converter for more conversion options.
For more pressure conversion questions, visit our FAQ page or explore our conversion guides.
Helpful Conversion Guides
Learn more about unit conversion with our comprehensive guides:
📚 How to Convert Units
Step-by-step guide to unit conversion with practical examples.
🔢 Conversion Formulas
Essential formulas for pressure and other conversions.
⚖️ Metric vs Imperial
Understand the differences between measurement systems.
⚠️ Common Mistakes
Learn about frequent errors and how to avoid them.
All Pressure Conversions
Other Pressure Units and Conversions
Explore other pressure units and their conversion options:
- Pascal (Pa) • Pound per Square Inch to Pascal
- Kilopascal (kPa) • Pound per Square Inch to Kilopascal
- Megapascal (MPa) • Pound per Square Inch to Megapascal
- Hectopascal (hPa) • Pound per Square Inch to Hectopascal
- Bar (bar) • Pound per Square Inch to Bar
- Millibar (mbar) • Pound per Square Inch to Millibar
- Atmosphere (atm) • Pound per Square Inch to Atmosphere
- Technical Atmosphere (at) • Pound per Square Inch to Technical Atmosphere
- Millimeter of Mercury (mmHg) • Pound per Square Inch to Millimeter of Mercury
- Inch of Mercury (inHg) • Pound per Square Inch to Inch of Mercury
Verified Against Authority Standards
All conversion formulas have been verified against international standards and authoritative sources to ensure maximum accuracy and reliability.
National Institute of Standards and Technology — Fundamental physical constants and unit conversions
Bureau International des Poids et Mesures — International System of Units (SI) definitions and standards
International Organization for Standardization — Quantities and units international standards series
Last verified: February 19, 2026