About Pressure Units

Pressure is force per unit area. The SI unit is the pascal (Pa). Standard atmospheric pressure at sea level is 101,325 Pa (1 atm). Tyre pressures use psi (pounds per square inch) in the US or bar in Europe. Blood pressure is measured in mmHg (millimetres of mercury).

Common Conversions

  • 1 atm = 101,325 Pa = 14.696 psi
  • 1 bar = 100,000 Pa ≈ 0.987 atm
  • 1 psi = 6,895 Pa
  • 1 mmHg = 133.3 Pa
  • 1 kPa = 0.145 psi

Practical Reference

  • Normal blood pressure: 120/80 mmHg
  • Car tyre pressure: 32–36 psi (2.2–2.5 bar)
  • Bicycle tyre: 80–130 psi
  • Deep sea at 1 km: ~100 atm
  • Aircraft cabin: ~0.75 atm (≈ 8,000 ft altitude)