Pressure Converter
Unit Converters
Convert pressure between Pa, kPa, MPa, mbar, hPa, bar, atm, psi, mmHg, inHg, and Torr. Free browser-based pressure converter.
All units at this value
Based on the current From value in Atmosphere (atm). Millibar (mbar) and hectopascal (hPa) are numerically equivalent; each is 100 Pa.
SI / Metric
- Pascal (Pa)
- Kilopascal (kPa)
- Megapascal (MPa)
- Millibar (mbar)100 Pa; same as hPa
- Hectopascal (hPa)100 Pa; same as mbar
Common
- Bar
- Atmosphere (atm)Current input
- Pounds per sq inch (psi)
Mercury
- Millimeter of mercury (mmHg)
- Inch of mercury (inHg)
- Torr
How to use this tool
- Enter a pressure value. Type the pressure value you want to convert in the "From" field.
- Select units. Choose the source and target pressure units from the dropdown menus. Millibars (mbar) and hectopascals (hPa) are separate choices with equal values.
- Read the result. The converted pressure and equivalent values in every supported unit appear instantly. Use the swap button to reverse the conversion.
Common pressure conversions
| Value | Equivalent |
|---|---|
| 1 atm | 101,325 Pa = 14.696 psi = 1.01325 bar |
| 1013.25 mbar | 1013.25 hPa = 101,325 Pa = 1 atm |
| 1 bar | 100,000 Pa = 14.504 psi = 0.9869 atm |
| 1 psi | 6,894.76 Pa = 0.0689 bar = 51.715 mmHg |
| 1 kPa | 1,000 Pa = 0.145 psi = 0.01 bar |
| 760 mmHg | 1 atm = 101,325 Pa |
| 29.921 inHg | 1 atm (standard) |
| 1 MPa | 1,000 kPa = 145.038 psi |
How pressure conversion works
All conversions pass through Pascals (Pa) as the base SI unit. The input value is multiplied by the source unit's Pascal factor, then divided by the target unit's Pascal factor. For example, 1 atm = 101,325 Pa, and 1 psi = 6,894.757 Pa, so 1 atm = 101,325 ÷ 6,894.757 ≈ 14.696 psi.
Pressure units explained
Pascal (Pa) is the SI unit of pressure, equal to one Newton per square meter. Millibar (mbar) and hectopascal (hPa) are numerically equivalent: 1 mbar = 1 hPa = 100 Pa. Hectopascals are widely used in weather reports, while millibars are common in vacuum ranges. Bar is 100,000 Pa and is commonly used in meteorology, engineering, and tire gauges in Europe. PSI (pounds per square inch) is the standard in the United States for tire pressure, hydraulics, and industrial equipment. mmHg / Torr are used in medicine (blood pressure) and vacuum systems.
Practical pressure reference
| Application | Typical pressure |
|---|---|
| Sea level atmospheric pressure | 1 atm = 101.325 kPa = 14.696 psi |
| Car tire (passenger vehicle) | ~220–250 kPa (~32–36 psi) |
| Bicycle tire (road) | ~550–900 kPa (~80–130 psi) |
| Normal blood pressure (systolic) | ~120 mmHg (~16 kPa) |
| Scuba tank (full) | ~20,000 kPa (~200 bar) |
| Deepest ocean (Mariana Trench) | ~108,600 kPa (~15,750 psi) |
| Diamond anvil cell (lab) | > 1,000,000 bar (1 Mbar) |
Gauge vs. absolute pressure
Absolute pressure is measured from true vacuum (0 Pa = perfect vacuum). Gauge pressure is measured relative to local atmospheric pressure (0 gauge = 1 atm absolute). Most everyday instruments — tire pressure gauges, blood pressure cuffs, HVAC gauges — read gauge pressure. Failure to distinguish between gauge and absolute causes errors in engineering calculations; always confirm which convention a formula or datasheet uses.
Conversion: Absolute = Gauge + Atmospheric (typically 101,325 Pa).
Vacuum levels
Vacuum is simply pressure below atmospheric. The mbar ranges below can also be entered as hPa, because 1 mbar = 1 hPa = 100 Pa. Common ranges:
| Level | Pressure range | Typical application |
|---|---|---|
| Rough vacuum | 1–100 mbar | Vacuum cleaners, food packaging |
| Medium vacuum | 0.1–1 mbar | Freeze-drying, distillation |
| High vacuum | <0.1 mbar (<10 Pa) | CRT displays, electron microscopes |
| Ultra-high vacuum | <10−9 mbar | Particle accelerators, space simulation |
Frequently asked questions
How do I convert psi to bar?
Multiply psi by 0.0689476. For example, 14.696 psi × 0.0689476 = 1.01325 bar (standard atmosphere). To convert bar to psi, multiply by 14.5038.
What is 1 atmosphere in Pa?
One standard atmosphere (atm) equals exactly 101,325 Pascals (101.325 kPa). It is 1,013.25 hPa or mbar, and is approximately 14.696 psi, 1.01325 bar, or 760 mmHg.
Are millibars and hectopascals the same?
Yes. One millibar (mbar) and one hectopascal (hPa) are each exactly 100 Pascals, so they have the same numerical value. Hectopascals are common in weather reports, while millibars are often used for vacuum ranges.
What is the difference between mmHg and Torr?
They are nearly identical: 1 Torr is defined as 1/760 of a standard atmosphere, which equals 101325/760 ≈ 133.322 Pa. One mmHg is also 133.322 Pa by convention, making 1 Torr ≈ 1 mmHg for practical purposes.
What units are used for tire pressure?
In the United States, tire pressure is measured in psi (pounds per square inch). Most of the world uses bar or kPa. A typical car tire runs 30–35 psi, which is about 2.07–2.41 bar or 207–241 kPa.
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