# Pressure Unit Converter

MPa, kPa, bar, psi and kgf/cm² — every unit at once.

- Page: https://jianzhujisuan.com/en/unit-pressure
- Category: Unit conversion (https://jianzhujisuan.com/en/c/unit-conversion)
- Chinese version: https://jianzhujisuan.com/zh/unit-pressure.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Value 30, From unit Megapascal (N/mm²) (MPa), To unit Pound per square inch (psi)): **Converted value 4351.13 psi**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Value | number | 30 | — |  |
| From unit | select | Megapascal (N/mm²) (MPa) | — |  |
| To unit | select | Pound per square inch (psi) | — |  |

## Formula

- **Base**: 1 MPa = 1 N/mm² = 1000 kPa = 1 000 000 Pa
- **Old metric**: 1 kgf/cm² = 0.0980665 MPa ≈ 0.1 MPa
- **Anglo-American**: 1 psi = 6.89476 kPa, 1 bar = 100 kPa
- **Heads**: 1 mH₂O = 9.80665 kPa, 1 atm = 10.33 mH₂O
- **Grade**: C30 concrete = 30 MPa = 30 N/mm² = 300 kgf/cm²

## Worked example

30 MPa is 300 kgf/cm², 4351.13 psi or 300 bar. A 1.0 MPa pipeline test equals 10.2 m of water head or 145.04 psi.

## Questions

### Why is concrete strength in MPa when old drawings say “200 grade”?

“Grade 200” meant 200 kgf/cm², which is 19.6 MPa, today's C20. Old codes used grades in kgf/cm² and new ones use MPa classes; the conversion is not a simple divide by ten — C20 matches 200, C30 matches 300, C15 matches 150 — the factor is always 0.098.

### How is pipeline test pressure set?

Water supply lines are tested at 1.5 times working pressure and not less than 0.6 MPa; fire mains at 1.5 times working pressure and not less than 1.4 MPa, never exceeding 1.5 times the nominal rating. Choose gauges whose range is 1.5-2 times the test pressure — an oversized gauge hides leaks in its reading error.

### Is 1 bar the same as “one kilo of pressure”?

Site talk of “one kilo” means 1 kgf/cm² = 0.098 MPa while 1 bar is 0.1 MPa, 2% apart — fine as a rough equivalence. But nameplate values in bar, psi and MPa must be converted properly: in a high-rise, 2% is the difference between adequate and inadequate pressure on the top floor.

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