Pressure Converter — kPa, bar, psi and atm

Convert between Pa, hPa, kPa, MPa, bar, mbar, atm, Torr, mmHg, psi and kgf/cm². Compare pressure values from weather reports, vacuum gauges, pipe specifications and tyre labels. Choose a common conversion or select any of the 11 units.

Enter a number to update the selected result, formula and full unit list. Swapping units keeps the input number unchanged; it does not move the result into the input. Calculations happen in your browser. Your input values and results are not sent to a server.

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Results are approximate displays rounded to at most 12 significant digits, not a claim of measurement accuracy. If any of the 11 conversions is outside the numerical range, full-table copy and CSV export are disabled rather than exporting an incomplete table. A valid selected result can still be copied.

Pa = atm × 101,325. To convert Pa to atm, divide by 101,325.

bar = kPa ÷ 100. To convert bar to kPa, multiply by 100.

atm = bar ÷ 1.01325. To convert atm to bar, multiply by 1.01325. One bar and one standard atmosphere are different pressures.

kPa = mmHg × 0.133322387415 using this tool's conventional factor. For kPa to mmHg, divide by the same factor. This is a unit conversion, not a medical assessment.

kPa ≈ psi × 6.89475729317. For kPa to psi, divide by the same factor. This written factor is rounded; the calculator derives its factor from the definitions of pound-force and inch.

• 1 Pa = 1 N/m²; 1 hPa = 1 mbar = 100 Pa; 1 kPa = 1,000 Pa; 1 MPa = 1,000,000 Pa.
• 1 atm = 101,325 Pa = 1,013.25 hPa = 760 Torr. These relationships are exact by definition.
• 1 bar = 100,000 Pa = 100 kPa, exactly.
• 1 psi ≈ 6,894.757 Pa. The factor uses the international inch and standard gravity for pound-force.
• 1 Torr = 101,325/760 Pa ≈ 133.322368421 Pa. This tool uses 133.322387415 Pa for 1 conventional mmHg. The units are very close, but not identical; the extra digits do not describe the accuracy of a physical mercury column.
• 1 kgf/cm² = 98,066.5 Pa = 0.980665 bar, exactly.

Absolute pressure is measured relative to a perfect vacuum. Gauge pressure is measured relative to ambient atmospheric pressure. Labels such as psia and psig, or abs/a and G/g, identify that reference.

Absolute pressure = gauge pressure + the atmospheric reference pressure used for the measurement or specification. Assuming a standard atmosphere would add 101,325 Pa, but actual atmospheric pressure varies with altitude and weather.

This tool changes units only. It does not convert psig to psia or otherwise add or subtract atmospheric pressure. Preserve the reference designation from your source. Negative values can represent gauge pressure; a numerical conversion does not establish that a value is physically appropriate for a particular system.