This pressure converter switches a reading between 14 units, including psi, bar, kilopascals, atmospheres, mmHg and inches of mercury. All conversions go through the pascal (1 Pa = 1 N/m²). Some factors are exact by definition: 1 bar = 100,000 Pa and 1 standard atmosphere = 101,325 Pa; 1 psi is about 6,894.76 Pa, so 1 bar ≈ 14.5038 psi.
On this page
How to use the pressure converter
- Enter the pressure you have, such as 32 from a tire placard.
- Choose its unit and the unit you need, for example psi to bar.
- Read the result. The pressure converter keeps full precision and rounds only what it displays.
Gauges usually show gauge pressure (psig), the amount above the surrounding air. Absolute pressure (psia) adds atmospheric pressure, about 14.696 psi at sea level. The pressure converter changes units only, so convert gauge to gauge or absolute to absolute.
What is pressure?
Pressure is force per unit area. The SI unit is the pascal (Pa), one newton per square meter. Tire pressure in the US is in psi, weather uses hectopascals or millibars, and one standard atmosphere is exactly 101,325 Pa.
Conversion formula
Every unit is stored as a multiple of the base unit, the pascal (Pa). To convert:
value in target unit = value × (factor of source unit ÷ factor of target unit)
where each factor is the size of the unit in pascals.
Common pressure conversions
| From | To | 1 unit equals |
|---|---|---|
| pascal (Pa) | pound per square inch (psi) | 0.0001450377 psi |
| pound per square inch (psi) | pascal (Pa) | 6,894.757 Pa |
| bar (bar) | pound per square inch (psi) | 14.50377 psi |
| pound per square inch (psi) | bar (bar) | 0.06894757 bar |
| standard atmosphere (atm) | pascal (Pa) | 101,325 Pa |
| millibar (mbar) | hectopascal (hPa) | 1 hPa |
| millimeter of mercury (mmHg) | pascal (Pa) | 133.3224 Pa |
| kilopascal (kPa) | pound per square inch (psi) | 0.1450377 psi |
| inch of mercury (inHg) | millibar (mbar) | 33.86389 mbar |
| megapascal (MPa) | pound per square inch (psi) | 145.0377 psi |
Pressure converter worked example
Convert 25 bars to pounds per square inch:
- Factor of bar = 100,000 Pa
- Factor of psi = 6,894.7573 Pa
- 25 × 100,000 ÷ 6,894.7573 = 362.5943 psi
Pressure unit reference
| Unit | Symbol | Group | Equals (Pa) |
|---|---|---|---|
| Pascal | Pa | SI | 1 |
| Kilopascal | kPa | SI | 1,000 |
| Megapascal | MPa | SI | 1,000,000 |
| Hectopascal | hPa | SI | 100 |
| Bar | bar | Metric | 100,000 |
| Millibar | mbar | Metric | 100 |
| Pound per Square Inch | psi | US/Imperial | 6,894.757293 |
| Standard Atmosphere | atm | Common | 101,325 |
| Torr | Torr | Common | 133.3223684 |
| Millimeter of Mercury | mmHg | Common | 133.3223874 |
| Inch of Mercury | inHg | US | 3,386.389 |
| Kilogram-force per Square Centimeter | kgf/cm² | Metric Engineering | 98,066.5 |
| Pound-force per Square Foot | psf | US Engineering | 47.88025898 |
| Dyne per Square Centimeter | dyn/cm² | CGS | 0.1 |
Reverse factors for each pressure unit
The reference table gives each unit in pascals. To go the other way, divide by that factor; the list below does the division for you.
- Kilopascal (kPa), SI: 1 kPa = 1,000 Pa, so 1 Pa = 0.001 kPa.
- Megapascal (MPa), SI: 1 MPa = 1,000,000 Pa, so 1 Pa = 1 × 10−6 MPa.
- Hectopascal (hPa), SI: 1 hPa = 100 Pa, so 1 Pa = 0.01 hPa.
- Bar (bar), Metric: 1 bar = 100,000 Pa, so 1 Pa = 1 × 10−5 bar.
- Millibar (mbar), Metric: 1 mbar = 100 Pa, so 1 Pa = 0.01 mbar.
- Pound per Square Inch (psi), US/Imperial: 1 psi = 6,894.757 Pa, so 1 Pa = 0.0001450377 psi.
- Standard Atmosphere (atm), Common: 1 atm = 101,325 Pa, so 1 Pa = 9.86923 × 10−6 atm.
- Torr (Torr), Common: 1 Torr = 133.3224 Pa, so 1 Pa = 0.007500617 Torr.
- Millimeter of Mercury (mmHg), Common: 1 mmHg = 133.3224 Pa, so 1 Pa = 0.007500616 mmHg.
- Inch of Mercury (inHg), US: 1 inHg = 3,386.389 Pa, so 1 Pa = 0.0002952998 inHg.
- Kilogram-force per Square Centimeter (kgf/cm²), Metric Engineering: 1 kgf/cm² = 98,066.5 Pa, so 1 Pa = 1.01972 × 10−5 kgf/cm².
- Pound-force per Square Foot (psf), US Engineering: 1 psf = 47.88026 Pa, so 1 Pa = 0.02088543 psf.
- Dyne per Square Centimeter (dyn/cm²), CGS: 1 dyn/cm² = 0.1 Pa, so 1 Pa = 10 dyn/cm².
Tire pressure chart: psi to bar and kPa
Car manuals in Europe and Asia often list tire pressure in bar or kPa, while US placards use psi. Values from the pressure converter:
| psi | bar | kPa |
|---|---|---|
| 26 | 1.79 | 179.3 |
| 28 | 1.93 | 193.1 |
| 30 | 2.07 | 206.8 |
| 32 | 2.21 | 220.6 |
| 35 | 2.41 | 241.3 |
| 36 | 2.48 | 248.2 |
| 40 | 2.76 | 275.8 |
| 44 | 3.03 | 303.4 |
| 50 | 3.45 | 344.7 |
| 80 | 5.52 | 551.6 |
| 100 | 6.89 | 689.5 |
Always use the pressure printed on your vehicle placard; the chart only translates units.
Weather pressure: hPa, mbar and inHg
Weather services report air pressure in hectopascals (hPa), which equal millibars, or in inches of mercury in the US. Standard sea-level pressure is 1013.25 hPa, or 29.92 inHg:
| hPa (mbar) | inHg | kPa |
|---|---|---|
| 980 | 28.94 | 98 |
| 990 | 29.23 | 99 |
| 1000 | 29.53 | 100 |
| 1013.25 | 29.92 | 101.33 |
| 1020 | 30.12 | 102 |
| 1030 | 30.42 | 103 |
Blood pressure uses millimeters of mercury: 120 mmHg is about 16.0 kPa. The pressure converter handles mmHg and torr, which differ by less than one part in a million.
Related converters and calculators
Pressure links force and area, so these tools pair well with the pressure converter:
- Force converter: newtons, pound-force and kilogram-force
- Area converter: square meters, square inches and more
- Tire size calculator: compare tire diameters
- Density converter: for fluid calculations
- Flow rate converter: gpm, L/min and m³/h
- Unit converter: other quantities
Sources
NIST Special Publication 811, Appendix B; BIPM: SI Brochure; US National Weather Service.
Questions about this calculator
What is the SI unit of pressure?
The SI unit of pressure is the pascal (Pa), one newton per square meter. The pressure converter stores every unit as a multiple of the pascal.
How do I convert psi to bar?
To convert psi to bar, divide by 14.5038 (or multiply by 0.0689476). For example, 32 psi = 2.21 bar.
How do I convert bar to psi?
To convert bar to psi, multiply by 14.5038. For example, 2.5 bar = 36.26 psi.
How do I convert kPa to psi?
To convert kPa to psi, divide by 6.89476. For example, 250 kPa = 36.26 psi.
How many psi is one atmosphere?
One standard atmosphere is 101,325 Pa, which is about 14.696 psi, 1.01325 bar or 760 mmHg.
What is the difference between psi and psig?
psig is gauge pressure, measured relative to the surrounding air; psia is absolute pressure. psia = psig + atmospheric pressure (about 14.696 psi at sea level).
Are these pressure conversion factors exact?
The bar, standard atmosphere and kilogram-force per square centimeter are exact by definition. The psi and mercury units are rounded to about 10 significant digits, following NIST SP 811.
Check the assumptions and units before relying on a result. Financial, tax and health estimates do not replace advice for your individual circumstances.
Report a calculation issue