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Pressure Conversion

Convert pressure between PSI, bar, pascal, atmosphere, torr, and 35+ units instantly. Essential for engineering, HVAC, and automotive applications. See also our Air Pressure Calculator and Bar to PSI Converter.

Pressure Conversion

Value:

bar
Result:10 bar=0.1450ksi (ksi)

Popular Pressure Converters:

bar to psipsi to barpsi to kpakpa to psi

What is a Pressure Converter?

A pressure converter is a tool that converts measurements between different units of pressure such as pascal, bar, PSI, atmosphere, and torr. It is essential for engineering, meteorology, tire maintenance, HVAC systems, and any application involving fluid or gas pressure.

History of Pressure Measurement

Torricelli invented the mercury barometer in 1643, enabling the first atmospheric pressure measurements. Blaise Pascal demonstrated that pressure decreases with altitude and formulated Pascal's law in the 1640s. The SI unit pascal (Pa) is named in his honor and equals one newton per square meter.

About This Pressure Converter

This pressure converter supports 35 different units including pascal, kilopascal, megapascal, bar, millibar, PSI, KSI, standard atmosphere, torr, mmHg, inHg, and various force-per-area combinations. It covers units used in engineering, meteorology, and industrial applications.

Understanding Pressure Measurement and Conversion

Pressure is force applied per unit area — it quantifies how concentrated a force is over a surface. When you inflate a tire to 32 psi, you are saying that every square inch of the tire's inner surface experiences 32 pounds of force. Pressure governs everything from weather patterns (atmospheric pressure) to blood flow (blood pressure in mmHg) to industrial processes (boiler pressure in bar or kPa).

The diversity of pressure units reflects the measurement's importance across many fields. Meteorologists use millibars or hectopascals, doctors use millimeters of mercury, tire gauges show psi or bar, scuba divers think in atmospheres, and engineers specify kilopascals or megapascals. The SI unit is the pascal (Pa), but because one pascal is very small (the pressure of a dollar bill resting on a table), practical units like kilopascal (kPa), bar, and atmosphere (atm) are more common.

Converting between pressure units requires knowing their relationships. The key anchor point is standard atmospheric pressure: 101,325 Pa = 1 atm = 1.01325 bar = 760 mmHg = 14.696 psi. From this single equivalence, all common pressure conversions can be derived.

How to Convert Between Pressure Units (Step-by-Step)

Pressure conversion is straightforward when you use pascals (or kilopascals) as your intermediate unit. Here is the systematic method:

  1. Identify your source pressure unit and value (e.g., 2.5 atm).
  2. Convert to pascals by multiplying by the unit's pascal equivalent. For atm: 2.5 × 101,325 = 253,312.5 Pa.
  3. Convert from pascals to your target unit by dividing by that unit's pascal equivalent. For psi: 253,312.5 ÷ 6,894.76 = 36.74 psi.
  4. Alternatively, if you know the direct conversion factor (e.g., 1 atm = 14.696 psi), multiply directly: 2.5 × 14.696 = 36.74 psi.
  5. Verify your answer: atmospheric pressure is about 14.7 psi or 1 bar, so 2.5 atm should be about 36.7 psi or 2.5 bar. Check that your result is in the right ballpark.
💡 Tip: Be careful with gauge pressure vs absolute pressure. Tire pressure of "32 psi" typically means 32 psi above atmospheric — the absolute pressure is 32 + 14.7 = 46.7 psia. Always clarify whether you are working with gauge (psig) or absolute (psia) pressure.

Essential Pressure Conversion Formulas

These are the most commonly needed pressure conversion relationships. Standard atmosphere (atm) serves as a convenient bridge between systems:

  • 1 pascal (Pa) = 1 newton per square meter (N/m²)
  • 1 kilopascal (kPa) = 1,000 Pa = 0.145038 psi
  • 1 bar = 100,000 Pa = 14.5038 psi
  • 1 atmosphere (atm) = 101,325 Pa = 1.01325 bar = 14.696 psi
  • 1 psi = 6,894.76 Pa = 0.068948 bar
  • 1 mmHg (torr) = 133.322 Pa
  • 1 atm = 760 mmHg = 29.921 inHg
  • 1 megapascal (MPa) = 1,000 kPa = 145.038 psi

Worked Examples — Pressure Conversions

Example 1: A tire is inflated to 35 psi. What is that pressure in bar and kilopascals?

Solution:

1 psi = 0.0689476 bar.

Multiply: 35 × 0.0689476 = 2.413 bar.

For kPa: 1 psi = 6.89476 kPa.

Multiply: 35 × 6.89476 = 241.3 kPa.

Answer: 35 psi = 2.413 bar = 241.3 kPa.

Example 2: Normal blood pressure is 120/80 mmHg. Express the systolic pressure (120 mmHg) in kilopascals.

Solution:

1 mmHg = 133.322 Pa.

Multiply: 120 × 133.322 = 15,998.6 Pa.

Convert to kPa: 15,998.6 ÷ 1,000 = 16.0 kPa.

Answer: 120 mmHg = 16.0 kPa (systolic blood pressure).

Example 3: A weather report shows atmospheric pressure of 1,013 hPa. What is that in inches of mercury (inHg)?

Solution:

1 hPa = 1 millibar = 100 Pa.

1,013 hPa = 101,300 Pa.

1 inHg = 3,386.39 Pa.

Divide: 101,300 ÷ 3,386.39 = 29.91 inHg.

Answer: 1,013 hPa = 29.91 inHg (near-standard atmospheric pressure).

Example 4: A scuba diver descends to 30 meters depth in seawater. What is the total pressure in atmospheres?

Solution:

Seawater pressure increases by approximately 1 atm per 10 meters depth.

At 30 m: pressure from water = 30 ÷ 10 = 3 atm.

Add atmospheric pressure at the surface: 3 + 1 = 4 atm total.

Answer: At 30 meters depth, total pressure = 4 atm (approximately 58.8 psi absolute).

Example 5: A hydraulic system operates at 20 MPa. Express this in psi.

Solution:

1 MPa = 145.038 psi.

Multiply: 20 × 145.038 = 2,900.8 psi.

Answer: 20 MPa = 2,901 psi (a common hydraulic system pressure).

Quick Reference — Common Pressure Conversions

This table covers the most frequently needed pressure unit equivalencies.

FromTo
1 pascal (Pa)0.000145 psi
1 kilopascal (kPa)0.145038 psi
1 bar14.5038 psi
1 atmosphere (atm)14.696 psi
1 psi6,894.76 Pa
1 mmHg (torr)133.322 Pa
1 inHg3,386.39 Pa
1 millibar (mbar)100 Pa
1 hectopascal (hPa)1 mbar
1 megapascal (MPa)145.038 psi
1 kgf/cm²98,066.5 Pa
1 atm760 mmHg
1 atm29.921 inHg
1 atm1.01325 bar

Pressure Measurement Systems Explained

The SI unit of pressure is the pascal (Pa), defined as one newton of force per square meter of area. While dimensionally elegant, the pascal is inconveniently small for everyday use — atmospheric pressure is 101,325 Pa. This led to practical alternatives: the kilopascal (kPa) for tire pressure and engineering, the hectopascal (hPa) for meteorology (numerically equal to the millibar), and the megapascal (MPa) for high-pressure industrial applications.

The bar was introduced as a convenient unit close to one atmosphere: 1 bar = 100,000 Pa (exactly), while 1 atm = 101,325 Pa. This 1.3% difference means bar and atm are often used interchangeably in casual contexts, but the distinction matters in precise work. The bar is now the standard unit for tire pressure in Europe and much of the world.

Legacy units persist in specialized fields. Doctors worldwide measure blood pressure in mmHg (millimeters of mercury) because early sphygmomanometers used mercury columns. Aviation uses inches of mercury (inHg) for altimeter settings. The psi (pounds per square inch) dominates in US industry and automotive applications. Each unit carries historical weight and practical convenience in its respective field, which is why pressure conversion remains a daily necessity across professions.

Where Pressure Conversion Matters

Automotive & Tire Maintenance

Tire pressure is specified in psi (US) or bar/kPa (Europe, Asia). A US car manual saying 32 psi needs to read 2.2 bar on a European gauge. Under-inflation by even 5 psi (0.35 bar) significantly affects fuel economy and tire wear.

Medicine & Healthcare

Blood pressure is universally measured in mmHg, but ventilator pressures use cmH₂O or mbar. IV fluid pressure may be in kPa. Medical professionals must convert fluently between these units.

Meteorology & Aviation

Weather maps show pressure in hPa or millibars. Pilots set altimeters in inHg (US) or hPa (ICAO standard). A pressure error of 1 hPa (0.03 inHg) causes a 27-foot altitude error.

Scuba Diving

Divers think in atmospheres or bar for depth-pressure relationships. Tank pressure is measured in psi (US) or bar (metric). Decompression tables require absolute pressure calculations.

Industrial & Hydraulic Systems

Hydraulic presses, injection molding machines, and pipeline systems use MPa, bar, or psi depending on country. A hydraulic system at 210 bar (3,045 psi) requires precise conversion for component selection.

HVAC & Refrigeration

Refrigerant pressures are critical for system diagnosis. Technicians use psi (US) or bar/kPa (metric) and must convert when using equipment or references from different regions.

Gauge Pressure vs Absolute Pressure

Most pressure instruments (tire gauges, blood pressure cuffs, industrial gauges) measure gauge pressure — the pressure above atmospheric. A tire at "32 psi" means 32 psi above the surrounding atmosphere, so the absolute pressure inside is 32 + 14.7 = 46.7 psia. This distinction is critical in engineering calculations involving gas laws (PV = nRT requires absolute pressure), altitude calculations, and vacuum systems. Vacuum is simply negative gauge pressure: a "perfect vacuum" is 0 psia = -14.7 psig = -1 atm gauge.

Why So Many Pressure Units Exist

Pressure units proliferated because different fields measured pressure with different instruments. Mercury barometers gave us mmHg and inHg. Water manometers gave cmH₂O and inH₂O. Weighted pistons on calibrated cylinders gave psi and kgf/cm². The atmosphere was defined from average sea-level barometric readings. The bar was created as a convenient decimal unit. Each instrument and tradition produced its own unit, and each persists because changing established practice in medicine, aviation, or industry would introduce dangerous confusion during the transition period.

Key Takeaways

  • Pressure is force per unit area. The SI unit is the pascal (1 Pa = 1 N/m²).
  • Standard atmosphere: 1 atm = 101,325 Pa = 1.01325 bar = 14.696 psi = 760 mmHg.
  • The bar (100,000 Pa) is close to but not exactly equal to 1 atm (101,325 Pa).
  • Always distinguish between gauge pressure and absolute pressure — they differ by 1 atm.
  • In medical contexts, mmHg remains standard for blood pressure despite being a non-SI unit.
  • For quick estimation: 1 bar ≈ 14.5 psi ≈ 100 kPa. Use these for mental checks.

Metric Conversion Factor Tables for Pressure Converter

Units to convertMultiply By The NumberConvert as Unit
Bar14.5038PSI
PSI0.0689476Bar
Bar100000Pascal (Pa)
Pascal (Pa)0.00001Bar
Bar0.986923Atmosphere (atm)
Atmosphere (atm)1.01325Bar
Atmosphere (atm)101325Pascal (Pa)
Atmosphere (atm)14.696PSI
PSI6894.76Pascal (Pa)
PSI6.89476Kilopascal (kPa)
Kilopascal (kPa)0.145038PSI
Torr133.322Pascal (Pa)
Atmosphere (atm)760Torr
Bar1000Millibar (mbar)

Pressureconverters & it's abbreviations

UnitAbbreviationUnitAbbreviationUnitAbbreviation
pascalPakilopascalkPamegapascalMPa
gigapascalGPaterapascalTPabarbar
millibarmbarmicrobarµbarpsipsi
ksiksiStandard atmosphereatmtorrTorr
millimeter mercurymmHginch mercuryinHginch waterinAq
micropascalµPamillipascalmPananopascalnPa
picopascalpPa

Frequently Asked Questions

How do I convert bar to PSI?

Multiply bar by 14.5038 to get PSI. For example, 2 bar = 2 × 14.5038 = 29.01 PSI.

What is standard atmospheric pressure?

Standard atmospheric pressure is 1 atm = 101,325 Pa = 1.01325 bar = 14.696 PSI = 760 mmHg. This is the average pressure at sea level.

What is the difference between PSI and bar?

PSI (pounds per square inch) is common in the US, while bar is used in most other countries. 1 bar = 14.5038 PSI. Bar is close to atmospheric pressure (1 atm ≈ 1.013 bar).

How do I convert kPa to PSI?

Multiply kilopascals by 0.145038 to get PSI. For example, 200 kPa = 200 × 0.145038 = 29.01 PSI.

What pressure unit is used for tire pressure?

In the US, tire pressure is measured in PSI (typically 30-35 PSI for cars). In Europe and most other countries, bar or kPa is used (2.0-2.5 bar or 200-250 kPa).

Complete list of Pressure conversion units and its conversion.