Convert Inches of Mercury to Gigapascals (inHg to GPa)

Formula

GPa = inHg × 0.000003386388640341

or GPa = inHg ÷ 295299.8330101

Derivation from SI units:

• 1 inHg = 13 595.1 kg/m³ × 9.80665 m/s² × 0.0254 m = 3386.388640341 Pa
• 1 GPa = 10⁹ Pa = 1000 MPa = 1 kN/mm²
• 1 inHg = 3386.388640341 Pa ÷ 1000000000 Pa per GPa = 0.000003386388640341 GPa

Both units are defined exactly, so the factor is exact. Inch of Mercury definition: inch of mercury; Gigapascal definition: gigapascal.

Worked examples

1. A reading of 15 inHg converts to 0.00005079582961 GPa.
   15 inHg × 0.00000338638864 = 0.00005079582961 GPa
2. A value of 29 inHg is 0.00009820527057 GPa.
   29 inHg × 0.00000338638864 = 0.00009820527057 GPa

Where it's used

Inches of Mercury are used for aircraft altimeter settings (standard 29.92 inHg), while gigapascals appear in young's modulus and shear modulus of metals, ceramics and composites. Both measure pressure, stress and differential pressure (force per unit area), so the conversion is a fixed factor.

Inch of Mercury 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 mercury, conventional (inHg)".
• The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.

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