What this converter does
This converter turns compressive strength in pounds per square inch into megapascals and back. It also handles ksi, N/mm² and kg/cm². Type a value, pick your units, and the answer appears instantly as you type.
A psi is defined exactly from the pound-force and inch, and a megapascal is one newton per square millimetre, so the conversion is exact. Working the other way? Use the MPa to psi converter.
The units it covers
Compressive strength is a stress — force per unit area — so every unit converts through the megapascal with a fixed ratio.
View all units & their values
| Unit | Symbol | Value | Mainly used |
|---|---|---|---|
| Megapascal | MPa | 1 | SI concrete strength (= N/mm²) |
| Pound per sq inch | psi | 0.006895 | US concrete strength |
| Kip per sq inch | ksi | 6.895 | US steel / high strength |
| Newton per mm² | N/mm² | 1 | Identical to MPa |
| Kg-force per cm² | kg/cm² | 0.09807 | Older metric / site tests |
The formula
Each unit has a fixed value in megapascals, so converting is one multiplication through the MPa:
result = value × factor_from ÷ factor_toWhere:
- value = the strength you typed, in the “from” unit
- factor_from = the “from” unit’s value in MPa
- factor_to = the “to” unit’s value in MPa
Worked example
Convert 4000 psi (a common US concrete strength) to MPa.
1 psi = 0.00689476 MPa4000 × 0.00689476 = 27.58 MPaSo 4000 psi concrete is about 27.6 MPa.
The units in this example
The US customary unit of stress. Concrete compressive strength is specified in psi (3000, 4000, 5000 psi) throughout North America.
- 1 psi = 0.006895 MPa
- 1000 psi = 6.895 MPa
- 1 psi ≈ 0.0703 kg/cm²
- 1 ksi = 1000 psi
The SI unit of stress, equal to one newton per square millimetre. Used for concrete grades (C25, C30, C40) in most of the world.
- 1 MPa = 145.0 psi
- 1 MPa = 1 N/mm²
- 1 MPa ≈ 10.20 kg/cm²
- 1 ksi = 6.895 MPa