Millimetres of mercury (conventional) to kilopascals (mmHg to kPa)

The formula

kPa = mmHg × 0.133322387415

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

• 1 mmHg = 13.5951 × g / cm³ × gₙ (standard gravity, CODATA 2022) × m / s² × mm = 133.322387415 Pa
• 1 kPa = 1000 × Pa = 1,000 Pa

Dividing the two SI sizes gives the factor: 0.133322387415, exact — every step above is a definition, not a measurement. The reverse factor is 7.50061575846.

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): 1,654.88 mmHg = 220.632 kPa — 1,654.88 × 0.1333223874 = 220.632
• Sea-level air (1 atm): 760 mmHg = 101.325 kPa — 760 × 0.1333223874 = 101.325
• A car tyre (European gauge) (2.2 bar): 1,650.14 mmHg = 220 kPa — 1,650.14 × 0.1333223874 = 220
• A systolic blood-pressure reading: 120 mmHg = 15.9987 kPa — 120 × 0.1333223874 = 15.9987

Frequently asked questions