Convert psi to Millibars

Formula

mbar = psi × 68.94757293168

Derivation from SI units:

• 1 psi = 1 lbf/in² = (0.45359237 kg × 9.80665 m/s²) ÷ (0.0254 m)² = 6894.757293168 Pa
• 1 mbar = 10⁻³ bar = 100 Pa = 1 hPa
• 1 psi = 6894.757293168 Pa ÷ 100 Pa per mbar = 68.94757293168 mbar

Both units are defined exactly, so the factor is exact. psi definition: psi; Millibar definition: millibar.

Worked examples

1. A reading of 14.7 psi converts to 1013.529322 mbar.
   14.7 psi × 68.94757293 = 1013.529322 mbar
2. A value of 60 psi is 4136.854376 mbar.
   60 psi × 68.94757293 = 4136.854376 mbar

Where it's used

psi are used for tyre pressure in the United States (about 30–35 psi for cars), while millibars appear in weather maps and barometers (sea level ≈ 1013 mbar). Both measure pressure, stress and differential pressure (force per unit area), so the conversion is a fixed factor.

psi to other pressure units

Frequently asked questions

Sources

• Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "pound-force per square inch (psi)".
• Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "millibar".

Last reviewed: 2026-10-15. Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.