Pressure Unit Converter
Unit ConversionConvert any pressure between pascals, kPa, MPa, bar, atmospheres, torr, mmHg, inHg, psi, ksi, kgf/cm² and inches of water. Type into any box and every other unit updates.
Bar
Metric
Atmosphere and Mercury
US and Engineering
1 Bar = 100,000 Pascals ⟷ 1 Pascal = 0.00001 Bar
1 Bar = 1,000 Hectopascals / Millibars ⟷ 1 Hectopascal / Millibar = 0.001 Bar
1 Bar = 100 Kilopascals ⟷ 1 Kilopascal = 0.01 Bar
1 Bar = 0.1 Megapascals ⟷ 1 Megapascal = 10 Bar
1 Bar = 0.986923 Atmospheres ⟷ 1 Atmosphere = 1.01325 Bar
1 Bar = 750.061683 Torr ⟷ 1 Torr = 0.00133322 Bar
1 Bar = 750.061576 mmHg ⟷ 1 mmHg = 0.00133322 Bar
1 Bar = 29.529983 Inches of Mercury (inHg) ⟷ 1 Inch of Mercury (inHg) = 0.0338639 Bar
1 Bar = 14.503774 PSI ⟷ 1 PSI = 0.0689476 Bar
1 Bar = 0.0145038 KSI ⟷ 1 KSI = 68.947573 Bar
1 Bar = 1.019716 kgf/cm² ⟷ 1 kgf/cm² = 0.980665 Bar
1 Bar = 401.864652 Inches of Water (60°F) ⟷ 1 Inch of Water (60°F) = 0.0024884 Bar
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Unit Conversion calculators
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SponsoredThis pressure converter shows one pressure in every common unit at the same time. Type a value into any box and the rest update as you type: pascals, hectopascals and millibars, kilopascals, megapascals, bar, standard atmospheres, torr, millimeters and inches of mercury, psi, ksi, kilograms-force per square centimeter and inches of water.
Pressure is force divided by the area it pushes on, so every pressure unit pairs a force with an area, or is defined from a unit that does. The SI unit is the pascal, one newton per square meter. The others are fixed multiples of it: a bar is exactly 100,000 pascals, one standard atmosphere is exactly 101,325 pascals, and a psi is about 6,894.757 pascals.
Most gauges read gauge pressure, measured from the surrounding air, so a negative reading means a partial vacuum. This converter accepts negative values down to a full vacuum, about -101,325 pascals or -14.7 psi, and clears the other boxes below that. You can type decimals or fractions, such as 2 1/2, and results show up to six decimal places.
Pressure Units
Pressure measurement units fall into three groups. Metric units are the pascal and its multiples, plus the bar. Reference units come from the weight of air or of a liquid column: the standard atmosphere, the torr, and millimeters or inches of mercury and of water. US customary units are built from the pound-force and the inch: psi and ksi. The table lists each one in pascals, from the conversion factors published by NIST in SP 811, Appendix B.9.
| Unit | Symbol | Value in Pascals | Value Status |
|---|---|---|---|
| Pascal | Pa | 1 Pa | Exact |
| Hectopascal (millibar) | hPa, mbar | 100 Pa | Exact |
| Kilopascal | kPa | 1,000 Pa | Exact |
| Megapascal | MPa | 1,000,000 Pa | Exact |
| Bar | bar | 100,000 Pa | Exact |
| Standard atmosphere | atm | 101,325 Pa | Exact |
| Technical atmosphere | at | 98,066.5 Pa | Exact |
| Kilogram-force per square centimeter | kgf/cm² | 98,066.5 Pa | Exact |
| Torr | Torr | 133.322368 Pa | Rounded (101,325/760 exactly) |
| Millimeter of mercury (conventional) | mmHg | 133.322387415 Pa | Exact |
| Inch of mercury (conventional) | inHg | 3,386.388640341 Pa | Exact |
| Inch of water (60°F) | inH2O | 248.84 Pa | Measured value (NIST) |
| Pound per square inch | psi | 6,894.757293 Pa | Rounded |
| Kip per square inch | ksi | 6,894,757.293168 Pa | Rounded |
Exact means the value follows from a definition, so the number in the table is complete. Rounded means the true value has more digits than shown. The two water column units are measured values that depend on the water temperature, so NIST gives them to a fixed number of digits. Blood pressure is a common place to meet millimeters of mercury, and the Mean Arterial Pressure Calculator takes systolic and diastolic readings in mmHg.
Pressure Conversion Chart
Read across a row: one unit on the left equals the value in each column. Values are rounded to seven significant figures.
| 1 Unit | Kilopascals | Bar | Atmospheres | PSI | mmHg |
|---|---|---|---|---|---|
| 1 bar | 100 kPa | 1 bar | 0.986923 atm | 14.50377 psi | 750.0616 mmHg |
| 1 atm | 101.325 kPa | 1.01325 bar | 1 atm | 14.69595 psi | 759.9999 mmHg |
| 1 psi | 6.894757 kPa | 0.0689476 bar | 0.068046 atm | 1 psi | 51.71493 mmHg |
| 1 kPa | 1 kPa | 0.01 bar | 0.00986923 atm | 0.145038 psi | 7.500616 mmHg |
| 1 mmHg | 0.133322 kPa | 0.00133322 bar | 0.00131579 atm | 0.0193368 psi | 1 mmHg |
| 1 inHg | 3.386389 kPa | 0.0338639 bar | 0.0334211 atm | 0.491154 psi | 25.4 mmHg |
How to Convert Pressure Units
- Multiply the value by the size of its unit in pascals, from the table above.
- Divide the result by the size of the target unit in pascals.
- Example: 30 psi is about 206.843 kPa (30 × 6,894.757 ÷ 1,000).
Going through pascals works for any pair of units, because every unit here is defined in pascals. Very large and very small results are easier to read in powers of ten, which the Scientific Notation Converter writes out for you.
Why Exact Factors Matter
Some converters store rounded factors, and the rounding shows up in the answer. With a rounded psi factor, 100 psi comes out as 689.48 kPa instead of 689.476 kPa. With 133.322 Pa used for a millimeter of mercury, one standard atmosphere comes out as 760.0021 mmHg instead of 759.99989 mmHg. This converter stores every defined factor in full and only rounds what it displays.
Chemistry problems usually need pressure in atmospheres or kilopascals. The Ideal Gas Law Calculator takes pressure in atmospheres, so a reading in psi or kPa can be converted in the boxes above first.
Common Pressure Conversion Mistakes
- Treating a bar as 1,000 pascals. A bar is 100,000 pascals; 1,000 pascals is a kilopascal.
- Forgetting that a millibar is 100 pascals, the same as a hectopascal, so millibars to kilopascals divides by 10.
- Mixing gauge and absolute pressure. Converting units never adds or removes the air pressure around the gauge.
- Treating 14.7 psi or 1 atm as the air pressure where you are. Both are fixed reference values; real air pressure changes with the weather and altitude.
Single Pressure Conversions
Single conversions between two pressure units, one page per pair.
- Bar to PSI Converter: 1 bar is about 14.503774 psi
- Bar to PSIG Converter: for gauge readings, 1 bar is about 14.503774 psi
- Bar to Atmospheres Converter: 1 bar is about 0.986923 standard atmospheres
- Kilopascals to PSI Converter: 1 kilopascal is about 0.145038 psi
- Kilopascals to Atmospheres Converter: 1 kilopascal is about 0.00986923 standard atmospheres
- Kilopascals to mmHg Converter: 1 kilopascal is about 7.500616 millimeters of mercury
- Megapascals to PSI Converter: 1 megapascal is about 145.037738 psi
- Megapascals to PSIG Converter: for gauge readings, 1 megapascal is about 145.037738 psi
- KSI to Megapascals Converter: 1 ksi is about 6.894757 megapascals
- KSI to PSI Converter: 1 ksi equals exactly 1,000 psi
- Pascals to PSI Converter: 1 pascal is about 0.000145038 psi
- Atmospheres to Pascals Converter: 1 standard atmosphere equals exactly 101,325 pascals
- PSI to Atmospheres Converter: 1 psi is about 0.068046 standard atmospheres
- PSIG to PSIA Converter: adds the standard atmosphere, about 14.6959 psi, to a gauge reading
- mmHg to Atmospheres Converter: 1 millimeter of mercury is about 0.00131579 standard atmospheres
- Torr to Atmospheres Converter: 1 torr is about 0.00131579 standard atmospheres
- kgf/cm² to PSI Converter: 1 kilogram-force per square centimeter is about 14.223343 psi
- PSI to Inches of Water Converter: 1 psi is about 27.707592 inches of water
Other Pressure Converters
Each converter below shows one pressure in many units at once, starting from a different unit.
- PSI Converter: psi to bar, kPa, atm, inHg, inches of water and more
- Kilopascal Converter: kilopascals to psi, bar, atm, hPa and more
- Megapascal Converter: megapascals to psi, ksi, bar, GPa and more
- Pascal Converter: pascals to hPa, kPa, MPa, GPa, psi and more
- Atmosphere Converter: standard atmospheres to psi, kPa, torr, mmHg and more
- Barometric Pressure Converter: inches of mercury to hPa, millibars, mmHg and more
Frequently Asked Questions
What is the difference between pressure and force?
Force is a push, measured in newtons or pounds-force. Pressure is that force divided by the area it acts on. The same force on a smaller area gives a higher pressure, which is why a pressure unit always combines a force and an area, such as newtons per square meter or pounds per square inch.
Which pressure unit should I use?
Use the unit your gauge, document or field expects. US tire placards and air compressors use psi; many other countries use kPa or bar. US weather reports use inches of mercury, while meteorologists elsewhere use hectopascals, which are the same as millibars. Science uses pascals and kilopascals, and blood pressure is given in mmHg.
How many psi is 1 bar?
1 bar is about 14.5038 psi. To convert bar to psi, multiply by about 14.5038; to convert psi to bar, divide by the same number.
What instrument measures pressure?
A barometer measures air pressure. A manometer measures a pressure by the height of a liquid column, which is where millimeters of mercury and inches of water come from. A pressure gauge on a tire, tank or compressor reads pressure above the surrounding air.
Can I enter a negative pressure?
Yes, down to a full vacuum. A negative value is a gauge reading below the surrounding air pressure. Nothing can go below a perfect vacuum, about -101,325 pascals or -14.7 psi on a gauge at standard air pressure, so the other boxes clear below that.
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