Bar to pounds per square inch (bar to psi)

The formula

psi = bar × 14.50377377

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

• 1 bar = 100 × kPa = 100,000 Pa
• 1 psi = lbf / in² = 6,894.75729317 Pa

Dividing the two SI sizes gives the factor: 14.503773773 (rounded for display; the underlying ratio is fixed by the definitions). The reverse factor is 0.0689475729317.

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): 2.20632 bar = 32 psi — 2.20632 × 14.50377377 = 32
• Sea-level air (1 atm): 1.01325 bar = 14.6959 psi — 1.01325 × 14.50377377 = 14.6959
• A car tyre (European gauge): 2.2 bar = 31.9083 psi — 2.2 × 14.50377377 = 31.9083
• A systolic blood-pressure reading (120 mmHg): 0.159987 bar = 2.32041 psi — 0.159987 × 14.50377377 = 2.32041

Frequently asked questions