Convert Decibars to Millimeters of Water (dbar to mmH2O)

Formula

mmH₂O = dbar × 1019.716212978

Derivation from SI units:

• 1 dbar = 10⁻¹ bar = 10⁴ Pa
• 1 mmH₂O = 1000 kg/m³ × 9.80665 m/s² × 0.001 m = 9.80665 Pa
• 1 dbar = 10000 Pa ÷ 9.80665 Pa per mmH₂O = 1019.716212978 mmH₂O

Both units are defined exactly, so the factor is exact. Decibar definition: decibar; Millimeter of Water definition: millimeter of water.

Worked examples

1. A reading of 50 dbar converts to 50985.81065 mmH₂O.
   50 dbar × 1019.716213 = 50985.81065 mmH₂O
2. A value of 1000 dbar is 1019716.213 mmH₂O.
   1000 dbar × 1019.716213 = 1019716.213 mmH₂O

Where it's used

Decibars are used for oceanography: CTD instruments report sea pressure in dbar, while millimeters of water appear in fan static pressure and duct design in Asia and Europe. Both measure pressure, stress and differential pressure (force per unit area), so the conversion is a fixed factor.

Decibar 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, "bar", with SI prefix deci (10⁻¹).
• 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, "millimeter of water, conventional (mmH2O)".

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