Convert Inches of Water (60 °F) to Millibars

Formula

mbar = inH₂O (60 °F) × 2.4884

Derivation from SI units:

• 1 inH₂O (60 °F) ≈ 999.0 kg/m³ × 9.80665 m/s² × 0.0254 m ≈ 248.84 Pa
• 1 mbar = 10⁻³ bar = 100 Pa = 1 hPa
• 1 inH₂O (60 °F) = 248.84 Pa ÷ 100 Pa per mbar = 2.4884 mbar

One unit is a measured value, so the factor is approximate. Inch of Water (60 °F) definition: inch of water (60 °F); Millibar definition: millibar.

Worked examples

1. A reading of 0.5 inH₂O (60 °F) converts to 1.2442 mbar.
   0.5 inH₂O (60 °F) × 2.4884 = 1.2442 mbar
2. A value of 7 inH₂O (60 °F) is 17.4188 mbar.
   7 inH₂O (60 °F) × 2.4884 = 17.4188 mbar

Where it's used

Inches of Water (60 °F) are used for older US gas-industry and flow-meter references, 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.

Inch of Water (60 °F) 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, "inch of water (60 °F)".
• 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.