Unit Conversion
Pressure Converter
Easily convert pressure units like Pascal (Pa), Bar, PSI, and Atmosphere (atm) with our free online Pressure Converter. Ideal for engineering, HVAC, automotive, and scientific calculations.
How Does Pressure Conversion Work?
Pressure is force per unit area, measured in Pascals (Pa) in the SI system — where 1 Pa = 1 Newton per square meter. Different industries use different units: meteorologists use millibars (mbar) and inches of mercury (inHg), engineers use PSI and bar, scientists use Pascals and atmospheres, and medical professionals use mmHg for blood pressure.
This converter supports 12 pressure units across metric (Pa, kPa, MPa, bar, mbar), imperial (PSI, PSF), atmospheric (atm, mmHg/Torr, inHg), and water column (mmH₂O, inH₂O) systems. All conversions use Pascals as the base unit. Enter a value, select your units, and get instant results.
How to Use This Converter
- Enter a pressure value and select the source unit
- Select the target unit you want to convert to
- Click Convert to see the result
- Use Swap to reverse the conversion direction
Common Use Cases
- Tire pressure checks
- Blood pressure readings
- Weather & barometry
- HVAC & plumbing
- Scuba & diving
- Industrial engineering
Quick Reference — Common Pressure Conversions
| From | To | Multiply By | Example |
|---|---|---|---|
| 1 bar | PSI | 14.5038 | 2 bar = 29.01 PSI |
| 1 PSI | bar | 0.06895 | 30 PSI = 2.07 bar |
| 1 atm | bar | 1.01325 | 1 atm ≈ 1.013 bar |
| 1 atm | PSI | 14.696 | 2 atm = 29.39 PSI |
| 1 atm | mmHg | 760 | 1 atm = 760 mmHg |
| 1 bar | kPa | 100 | 3 bar = 300 kPa |
| 1 PSI | kPa | 6.8948 | 35 PSI = 241.3 kPa |
| 1 atm | inHg | 29.9213 | 1 atm ≈ 29.92 inHg |
| 1 MPa | PSI | 145.038 | 0.5 MPa = 72.5 PSI |
| 1 mbar | Pa | 100 | 1013 mbar = 101,300 Pa |
Understanding Pressure Units
Metric & SI Units
| Pa | SI base unit — very small; used in acoustics, aerodynamics |
| kPa | Tire pressure (outside US), weather, HVAC systems |
| MPa | Material strength, hydraulic systems, concrete specs |
| bar | Industrial standard in Europe; scuba diving, compressors |
| mbar | Meteorology (= hPa); weather maps, barometers |
Imperial & Atmospheric Units
| PSI | US standard — tire pressure, air tools, plumbing |
| PSF | Structural engineering, wind load calculations |
| atm | Reference standard; 1 atm = sea-level air pressure |
| mmHg | Blood pressure, vacuum systems (= Torr) |
| inHg | US weather reports, aviation altimeter settings |
Real-World Pressure Comparisons
| Scenario | Pressure | Equivalent |
|---|---|---|
| Outer space (near vacuum) | ~0 Pa | 0 atm |
| Mount Everest summit | 33.7 kPa | 0.33 atm / 4.89 PSI |
| Standard atmosphere (sea level) | 101.325 kPa | 1 atm / 14.7 PSI / 760 mmHg |
| Normal blood pressure (systolic) | 16 kPa | 120 mmHg |
| Car tire (passenger) | 220–240 kPa | 32–35 PSI / 2.2–2.4 bar |
| Bicycle tire (road) | 550–830 kPa | 80–120 PSI / 5.5–8.3 bar |
| Scuba tank (full) | 20 MPa | 200 bar / 2,900 PSI |
| Deepest ocean (Mariana Trench) | 108.6 MPa | 1,071 atm / 15,750 PSI |
FAQ – Pressure Converter
What is a pressure converter?
A pressure converter is a tool that converts measurements between different units of pressure, such as PSI to bar, atmospheres to mmHg, or kilopascals to PSI. It's essential for engineering, automotive, HVAC, meteorology, medical, and scientific applications where different industries use different pressure units.
What is the difference between PSI and bar?
PSI (pounds per square inch) is the standard pressure unit in the US, while bar is the standard in Europe and most other countries. 1 bar = 14.5038 PSI, and 1 PSI = 0.06895 bar. For tire pressure, US gauges read in PSI (typically 30–35 for cars) while European gauges read in bar (2.0–2.4). They measure the same thing — just different scales.
What is standard atmospheric pressure?
Standard atmospheric pressure at sea level is defined as exactly 101,325 Pa = 1 atm = 1.01325 bar = 14.696 PSI = 760 mmHg = 29.92 inHg = 1013.25 mbar. This is the baseline reference for most pressure measurements. Actual atmospheric pressure varies with weather and altitude.
Why is blood pressure measured in mmHg?
Blood pressure is measured in millimeters of mercury (mmHg) because early sphygmomanometers used a column of mercury to measure pressure. A reading of 120/80 mmHg means the systolic pressure pushes mercury up 120 mm and diastolic 80 mm. Despite modern digital devices, mmHg remains the standard unit by medical convention worldwide.
What pressure unit is used for tire pressure?
In the US, tire pressure is measured in PSI (typically 30–35 PSI for passenger cars, 80–120 PSI for road bicycles). In Europe and most other countries, bar or kPa is used (2.0–2.4 bar for cars). Your vehicle's recommended pressure is on a sticker inside the driver's door jamb. Always measure when tires are cold.
What is the difference between gauge and absolute pressure?
Absolute pressure is measured relative to a perfect vacuum (0 Pa). Gauge pressure is measured relative to atmospheric pressure. A tire gauge reading 32 PSI means 32 PSI above atmospheric pressure, so the absolute pressure is 32 + 14.7 = 46.7 PSI. This converter works with the numerical values you enter — specify gauge or absolute based on your context.
What pressure units are used in weather forecasting?
Meteorologists use millibars (mbar) or hectopascals (hPa) — they're identical (1 mbar = 1 hPa = 100 Pa). US weather reports also use inches of mercury (inHg). Standard sea-level pressure is 1013.25 mbar / 29.92 inHg. Low pressure systems (below ~1000 mbar) bring storms; high pressure (above ~1020 mbar) brings clear weather.
Is a Torr the same as mmHg?
Nearly identical. 1 Torr is defined as exactly 1/760 of a standard atmosphere, which equals 133.322 Pa. 1 mmHg equals 133.322 Pa at 0°C under standard gravity. The difference is negligible (less than 0.000015%) and they're used interchangeably in practice. Torr is named after Evangelista Torricelli, who invented the barometer.
How does altitude affect pressure?
Atmospheric pressure decreases with altitude because there's less air above you. It drops roughly 12 Pa per meter (or 1 inHg per 1,000 feet) near sea level. At 5,500 m (18,000 ft), pressure is about half of sea level. At the top of Mount Everest (8,849 m), it's about one-third. This is why aircraft cabins are pressurized and why cooking times change at high altitude.
What pressure units are used in scuba diving?
Scuba diving uses bar (Europe) or PSI (US) for tank pressure — a full tank is typically 200 bar / 3,000 PSI. Underwater depth pressure is measured in atmospheres: every 10 meters (33 feet) of seawater adds approximately 1 atm. At 30 m depth, the total pressure is about 4 atm (1 atmospheric + 3 from water).