Convert Atmospheres to Inches of Water (60 °F)

Formula

inH₂O (60 °F) = atm × 407.189358624

Derivation from SI units:

• 1 atm = 101 325 Pa (exact, by definition)
• 1 inH₂O (60 °F) ≈ 999.0 kg/m³ × 9.80665 m/s² × 0.0254 m ≈ 248.84 Pa
• 1 atm = 101325 Pa ÷ 248.84 Pa per inH₂O (60 °F) = 407.189358624 inH₂O (60 °F)

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

Worked examples

1. A reading of 1.5 atm converts to 610.7840379 inH₂O (60 °F).
   1.5 atm × 407.1893586 = 610.7840379 inH₂O (60 °F)
2. A value of 10 atm is 4071.893586 inH₂O (60 °F).
   10 atm × 407.1893586 = 4071.893586 inH₂O (60 °F)

Where it's used

Atmospheres are used for chemistry and gas laws (STP and NTP conditions), while inches of water (60 °F) appear in older US gas-industry and flow-meter references. Both measure pressure, stress and differential pressure (force per unit area), so the conversion is a fixed factor.

Atmosphere 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, "atmosphere, standard (atm)".
• 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)".

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