Convert Pounds per Cubic Inch to Pounds per Gallon

Formula

lb/gal = lb/in³ × 231

Derivation from SI units:

• 1 lb/in³ = 0.45359237 kg ÷ 1.6387064 × 10⁻⁵ m³ = 27 679.9047 kg/m³
• 1 lb/gal = 0.45359237 kg ÷ 0.003785411784 m³ = 119.8264273 kg/m³
• 1 lb/in³ = 27679.9047102 kg/m³ ÷ 119.8264273169 kg/m³ per lb/gal = 231 lb/gal

Both units are defined exactly, so the factor is exact. Pound per Cubic Inch definition: pound per cubic inch; Pound per Gallon definition: pound per gallon.

Worked examples

1. A reading of 0.16 lb/in³ converts to 36.96 lb/gal.
   0.16 lb/in³ × 231 = 36.96 lb/gal
2. A value of 0.32 lb/in³ is 73.92 lb/gal.
   0.32 lb/in³ × 231 = 73.92 lb/gal

Where it's used

Pounds per Cubic Inch are used for metal densities (steel ≈ 0.284 lb/in³, aluminium ≈ 0.098 lb/in³), while pounds per gallon appear in drilling-mud weight in the oil and gas industry (ppg). Both measure density (mass per unit volume) and mass concentration, so the conversion is a fixed factor.

Pound per Cubic Inch to other density 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 per cubic inch (lb/in³)".
• 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 per gallon (U.S.)".

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