Pressure unit converter
Convert kgf/cm², bar, psi, MPa, kPa and mH₂O in one place, for pipe pressure tests, pump head and steam pressure where units get mixed on site. Gauge and absolute pressure and conversion tables are below.
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Pressure units at a glance
The SI unit of pressure is the pascal (Pa = N/m²); building services work in kPa and MPa. 1 MPa = 1,000 kPa = 1,000,000 Pa, and 1 bar = 100 kPa, so 1 MPa = 10 bar.
One kgf/cm² is a force of 1 kgf (9.80665 N) on 1 cm², or 98.0665 kPa. It differs from the bar by about 2 %, so 1 kgf/cm² ≈ 1 bar ≈ 0.1 MPa is fine for a rough check, but test and design pressures should be converted with the exact factor. One psi (lbf/in²) is 6.89476 kPa, and 1 kgf/cm² = 14.2233 psi.
Pressure conversion matrix (1 unit = other units)
Read how much 1 of the row unit is in each column unit (six significant digits). Same factors as the converter above.
| Unit | kPa | MPa | bar | kgf/cm² | psi | mH₂O | mmHg |
|---|---|---|---|---|---|---|---|
| 1 kPa | 1 | 0.001 | 0.01 | 0.0101972 | 0.145038 | 0.101972 | 7.50062 |
| 1 MPa | 1,000 | 1 | 10 | 10.1972 | 145.038 | 101.972 | 7,500.62 |
| 1 bar | 100 | 0.1 | 1 | 1.01972 | 14.5038 | 10.1972 | 750.062 |
| 1 kgf/cm² | 98.0665 | 0.0980665 | 0.980665 | 1 | 14.2233 | 10 | 735.559 |
| 1 psi | 6.89476 | 0.00689476 | 0.0689476 | 0.070307 | 1 | 0.70307 | 51.7149 |
| 1 atm | 101.325 | 0.101325 | 1.01325 | 1.03323 | 14.6959 | 10.3323 | 760 |
| 1 mmHg | 0.133322 | 0.000133322 | 0.00133322 | 0.00135951 | 0.0193368 | 0.0135951 | 1 |
| 1 inHg | 3.38639 | 0.00338639 | 0.0338639 | 0.0345316 | 0.491154 | 0.345316 | 25.4 |
| 1 mH₂O | 9.80665 | 0.00980665 | 0.0980665 | 0.1 | 1.42233 | 1 | 73.5559 |
| 1 mmAq | 0.00980665 | 0.00000980665 | 0.0000980665 | 0.0001 | 0.00142233 | 0.001 | 0.0735559 |
| 1 Pa | 0.001 | 0.000001 | 0.00001 | 0.0000101972 | 0.000145038 | 0.000101972 | 0.00750062 |
Gauge pressure and absolute pressure
A pressure gauge reads gauge pressure, measured from the surrounding atmosphere as zero. Gauge pressure = absolute pressure − atmospheric pressure, and standard atmospheric pressure is 101.325 kPa = 1.03323 kgf/cm² = 14.696 psi.
Append g (gauge) or a (absolute) to tell them apart: kPa(g) and kPa(a), psig and psia, barg and bara. On Korean and Japanese drawings, kgf/cm²G is gauge and kgf/cm²A is absolute. Steam tables and saturation temperatures use absolute pressure, so add atmospheric pressure to the gauge reading before looking them up.
Gauge to absolute pressure table
Gauge pressure plus standard atmospheric pressure (101.325 kPa). Actual atmospheric pressure changes with weather and altitude (about 90 kPa at 1,000 m).
| Gauge kgf/cm²G | kPa(a) | bar(a) | kgf/cm²(a) | psia |
|---|---|---|---|---|
| 0 | 101.33 | 1.013 | 1.033 | 14.70 |
| 1 | 199.39 | 1.994 | 2.033 | 28.92 |
| 2 | 297.46 | 2.975 | 3.033 | 43.14 |
| 3 | 395.52 | 3.955 | 4.033 | 57.37 |
| 5 | 591.66 | 5.917 | 6.033 | 85.81 |
| 7 | 787.79 | 7.878 | 8.033 | 114.26 |
| 10 | 1,081.99 | 10.820 | 11.033 | 156.93 |
| 16 | 1,670.39 | 16.704 | 17.033 | 242.27 |
| 20 | 2,062.66 | 20.627 | 21.033 | 299.16 |
Common kgf/cm² values
Values often seen in pipe pressure tests, pump discharge and steam pressure. A gauge value stays a gauge value after conversion.
| kgf/cm² | kPa | MPa | bar | psi | mH₂O |
|---|---|---|---|---|---|
| 1 | 98.0665 | 0.0980665 | 0.980665 | 14.2233 | 10 |
| 2 | 196.133 | 0.196133 | 1.96133 | 28.4467 | 20 |
| 3 | 294.1995 | 0.2941995 | 2.941995 | 42.67 | 30 |
| 5 | 490.3325 | 0.4903325 | 4.903325 | 71.1167 | 50 |
| 7 | 686.4655 | 0.6864655 | 6.864655 | 99.5634 | 70 |
| 10 | 980.665 | 0.980665 | 9.80665 | 142.233 | 100 |
| 16 | 1,569.064 | 1.569064 | 15.69064 | 227.573 | 160 |
| 20 | 1,961.33 | 1.96133 | 19.6133 | 284.467 | 200 |
| 30 | 2,941.995 | 2.941995 | 29.41995 | 426.7 | 300 |
Water head in mH₂O and kPa
Water head expresses pressure as a height of water and is converted with p = ρgh. The conventional definition uses water at 1,000 kg/m³ and standard gravity 9.80665 m/s², so 1 mH₂O = 9.80665 kPa and 10 mH₂O = 98.0665 kPa ≈ 1 kgf/cm². One mmH₂O (mmAq) is one thousandth of that.
A pump head of 30 m is about 294 kPa (2.94 bar, 3.0 kgf/cm²). Real water is lighter when warm (about 983 kg/m³ at 60 °C), so the same height gives slightly less pressure. Use the pump head calculator for detailed head calculations.
Sources
- NIST Special Publication 811 (2008), Appendix B: conversion factors for bar, kgf/cm², psi, atm, mmHg and mmH₂O
- CGPM 1901, standard acceleration of gravity g = 9.80665 m/s²; CGPM 1954, standard atmosphere 101.325 kPa
- ISO 80000-4:2019 Quantities and units, Part 4: Mechanics (pressure and gauge pressure)
Frequently asked questions
How do I convert kgf/cm² to MPa and bar?
1 kgf/cm² = 0.0980665 MPa = 0.980665 bar. So 10 kgf/cm² is 0.981 MPa (9.81 bar), and a common test pressure of 15 kgf/cm² is 1.47 MPa. The other way, 1 MPa = 10.197 kgf/cm² and 1 bar = 1.0197 kgf/cm².
What is the difference between gauge and absolute pressure?
Gauge pressure is measured from atmospheric pressure as zero (what a pressure gauge shows); absolute pressure is measured from a perfect vacuum. Absolute = gauge + atmospheric pressure (standard 101.325 kPa), so 7 kgf/cm² gauge is 787.79 kPa absolute (about 8.03 kgf/cm²A). Look up steam tables and saturation temperatures with absolute pressure.
How many kPa is a water head of 10 mH₂O?
Assuming water at 1,000 kg/m³ and standard gravity 9.80665 m/s², 10 mH₂O = 10 × 9.80665 = 98.07 kPa (about 1 kgf/cm², 0.98 bar). 1 mH₂O = 9.80665 kPa, and 100 kPa is 10.2 mH₂O. Warm water is less dense, so the same height gives slightly less pressure.
Last updated 2026-11-09.