Pressure Converter
Convert pressure between PSI, bar, atmospheres, kPa, mmHg, inHg, and Pascal. Includes gauge vs absolute pressure, altitude correction, and reference pressures.
Converted Pressure
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PSI
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Bar —
atm —
kPa —
mmHg —
inHg —
Pa —
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Pressure Conversions
Absolute Pressure (PSI) —
Gauge Pressure (PSI) —
Bar (absolute) —
kPa (absolute) —
Reference Pressures
Local Atmospheric Pressure —
Pressure at Water Depth —
How to Use This Calculator
- Enter your pressure value.
- Select the from unit and to unit.
- The converted value appears instantly. Use the Extended tab to see all units at once.
Formula
All units are converted through Pascal (Pa) as the base unit.
1 PSI = 6,894.757 Pa | 1 bar = 100,000 Pa | 1 atm = 101,325 Pa | 1 kPa = 1,000 Pa
Example
Example: Convert 30 PSI to bar: 30 × 6,894.757 ÷ 100,000 = 2.0684 bar
Frequently Asked Questions
- 1 bar equals exactly 14.503774 PSI (pounds per square inch). Conversely, 1 PSI = 0.0689476 bar. The bar is defined as exactly 100,000 Pascals (100 kPa), slightly less than 1 standard atmosphere (101,325 Pa = 1.01325 bar = 14.696 PSI). Common conversions: 1 bar = 14.504 PSI; 2 bar = 29.008 PSI; 3 bar = 43.511 PSI; 1.5 bar = 21.756 PSI. Car tire pressure: 2.2–2.5 bar = 32–36 PSI. Bicycle tires: road bikes 6–9 bar (87–130 PSI); mountain bikes 1.5–3 bar (22–44 PSI). Bar is the preferred unit for tire pressure in most of the world, while PSI is used in the US and UK. The millibar (mbar) is used in meteorology: standard sea-level pressure = 1013.25 mbar = 101.325 kPa.
- Absolute pressure is measured relative to a perfect vacuum (zero pressure). Gauge pressure (PSIG, barg) is measured relative to the local atmospheric pressure, which is approximately 14.696 PSI (101.325 kPa) at sea level. The relationship is: Absolute pressure = Gauge pressure + Atmospheric pressure. For example, a tire inflated to 32 PSIG (gauge) has an absolute pressure of 32 + 14.696 = 46.696 PSIA. Negative gauge pressure (vacuum) indicates pressure below atmospheric. PSIA (absolute) is used in thermodynamic calculations, engine performance analysis, and gas law calculations. PSIG (gauge) is used for everyday practical measurements like tire pressure, plumbing systems, and pneumatic tools. When a pressure gauge reads zero, the absolute pressure is still 14.696 PSI at sea level — you are just measuring the difference from atmosphere.
- 1 standard atmosphere (atm) = 14.6959 PSI = 101,325 Pa = 1.01325 bar = 1.01325 bar = 760 mmHg = 29.9213 inHg = 1,033.23 cmH2O. This is the defined standard atmospheric pressure at sea level, approximately equal to the mean air pressure at sea level at latitude 45°N. One atm was historically defined as the pressure exerted by a 760 mm column of mercury at 0°C. In practice, actual atmospheric pressure varies with altitude, weather, and temperature: at 1,000 m altitude, atmospheric pressure is about 89.88 kPa (13.04 PSI); at 3,000 m, about 70.11 kPa (10.17 PSI). Scuba diving uses "atmospheres" as a depth pressure unit: every 10 m of seawater adds approximately 1 atm (14.7 PSI) of pressure.
- Typical passenger car tire pressure is 30–36 PSI, which equals approximately 207–248 kPa (2.07–2.48 bar). Most car manufacturers recommend 32–35 PSI (220–241 kPa) for standard tires. Tire pressure is listed on a sticker inside the driver's door jamb or in the owner's manual — not on the tire sidewall, which shows the maximum pressure. Cold inflation pressure is recommended: check tires when cold (not driven in the past 3 hours or driven less than 1.5 km). Tires lose approximately 1–2 PSI (7–14 kPa) per month naturally and 1 PSI for every 10°F (5.6°C) drop in temperature. Low tire pressure reduces fuel efficiency by 0.2–0.5% per PSI underinflation and accelerates tread wear. Truck tires typically run at 80–120 PSI (552–827 kPa). Bicycle road tires: 90–130 PSI (620–896 kPa).
- mmHg stands for millimeters of mercury — the height in millimeters of a mercury column that exerts the measured pressure due to gravity. It is also called a Torr (after Evangelista Torricelli, inventor of the barometer). 1 mmHg = 1 Torr = 133.322 Pa = 0.019337 PSI. Standard atmospheric pressure = 760 mmHg = 101,325 Pa. mmHg is used primarily in medicine for blood pressure (normal: 120/80 mmHg systolic/diastolic), intraocular pressure (normal: 10–21 mmHg), and intracranial pressure. In meteorology, atmospheric pressure was historically measured in mmHg or inHg; modern practice uses hPa (hectopascals) or mbar, where 1 hPa = 1 mbar = 0.75006 mmHg. The Torr and mmHg are nearly identical but technically differ by about 0.000015%.