Convert Pounds per Cubic Foot to Pounds per Gallon

Formula

lb/gal = lb/ft³ × 0.1336805555556

or lb/gal = lb/ft³ ÷ 7.480519480519

Derivation from SI units:

• 1 lb/ft³ = 0.45359237 kg ÷ 0.028316846592 m³ = 16.018463374 kg/m³
• 1 lb/gal = 0.45359237 kg ÷ 0.003785411784 m³ = 119.8264273 kg/m³
• 1 lb/ft³ = 16.01846337396 kg/m³ ÷ 119.8264273169 kg/m³ per lb/gal = 0.1336805555556 lb/gal

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

Worked examples

1. A reading of 30 lb/ft³ converts to 4.010416667 lb/gal.
   30 lb/ft³ × 0.1336805556 = 4.010416667 lb/gal
2. A value of 110 lb/ft³ is 14.70486111 lb/gal.
   110 lb/ft³ × 0.1336805556 = 14.70486111 lb/gal

Where it's used

Pounds per Cubic Foot are used for concrete, soil and aggregate densities (normal concrete ≈ 145–150 pcf), 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 Foot 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 foot (lb/ft³)".
• 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.