Pounds per square inch to megapascals (psi to MPa)

The formula

MPa = psi × 0.006894757293

Where the factor comes from — each unit by its definition, then its size in SI:

• 1 psi = lbf / in² = 6,894.75729317 Pa
• 1 MPa = 1000 × kPa = 1,000,000 Pa

Dividing the two SI sizes gives the factor: 0.00689475729317 (rounded for display; the underlying ratio is fixed by the definitions). The reverse factor is 145.03773773.

Pressure is force per area; the pascal is one newton per square metre. Tyres are quoted in psi or bar, weather in hPa, blood pressure in mmHg and gas laws in pascals or atmospheres.

Worked examples

• A car tyre (US gauge): 32 psi = 0.220632 MPa — 32 × 0.006894757293 = 0.220632
• Sea-level air (1 atm): 14.6959 psi = 0.101325 MPa — 14.6959 × 0.006894757293 = 0.101325
• A car tyre (European gauge) (2.2 bar): 31.9083 psi = 0.22 MPa — 31.9083 × 0.006894757293 = 0.22
• A systolic blood-pressure reading (120 mmHg): 2.32041 psi = 0.0159987 MPa — 2.32041 × 0.006894757293 = 0.0159987

Frequently asked questions