g/cm³ to lb/ft³

A European steel spec says 7.85 g/cm³. The US fabricator estimating plate weight wants pounds per cubic foot: 490. The conversion factor, 62.427961, is the density of water in US units — because 1 g/cm³ is water, and water is 62.4 lb/ft³. Every material's g/cm³ value, multiplied by 62.4, becomes its lb/ft³ value.

1 g/cm³ = 62.4279605761 lb/ft³, and 1 lb/ft³ = 0.016018463374 g/cm³. The conversion is a single fixed factor: multiply g/cm³ by 62.4279605761. Worked: 10 g/cm³ = 624.27960576 lb/ft³; 100 g/cm³ = 6,242.79605761 lb/ft³.

By EnginStack Editorial Team | Reviewed against NIST, BIPM and primary-source documentation About →
g/cm³
168.55549356 lb/ft³
2.7 g/cm³ = 168.55549356 lb/ft³ 2.7 lb/ft³ = 0.04324985 g/cm³

Source: NIST SP 811 and the 1959 yard-and-pound agreement (0.9144 m, 0.45359237 kg). Every decimal place in the factor above is a defined constant, not a measurement.

g/cm³ to lb/ft³

A European steel spec says 7.85 g/cm³. The US fabricator estimating plate weight wants pounds per cubic foot: 490. The conversion factor, 62.427961, is the density of water in US units — because 1 g/cm³ is water, and water is 62.4 lb/ft³. Every material's g/cm³ value, multiplied by 62.4, becomes its lb/ft³ value.

lb/ft³ = g/cm³ × 62.427961
1 g/cm³ = 62.427961 lb/ft³ — water's density in US customary units
The factor is exact — derived from SI definitions and the 1959 yard/pound agreement.

Worked Examples

Example 1: Convert water for a US fabricator

1 × 62.427961 = 62.43 lb/ft³

Example 2: Convert a European steel spec into US units

7.85 × 62.427961 = 490.1 lb/ft³

Example 3: Convert aluminum into US units

2.7 × 62.427961 = 168.6 lb/ft³

Common g/cm³ to lb/ft³ Conversions

g/cm³lb/ft³Material / context
1 g/cm³62.43 lb/ft³Water — the bridge unit.
0.917 g/cm³57.2 lb/ft³Ice.
2.7 g/cm³168.6 lb/ft³Aluminum.
7.85 g/cm³490 lb/ft³Carbon steel.
8.96 g/cm³559 lb/ft³Copper.
13.6 g/cm³849 lb/ft³Mercury.
19.3 g/cm³1,205 lb/ft³Gold.

Engineering Context

Density links the mass and volume families on this site — it is their ratio. For the mass numerator, the kg to g and lbs to kg converters carry the same 1959 constants that appear here; for the volume denominator, the liters to mL and cubic feet to cubic meters pages supply the cubed lengths. The density hub collects all ten converters in this family.

The 62.4 figure is memorized by every US concrete and earthwork engineer long before anyone tells them where it comes from: a 1959 pound over a 1959 foot, cubed, then inverted. That provenance matters at the edges. Because the foot and the pound were both redefined by the 1959 agreement, the number is exact to the digits shown, not a measured approximation, so a converted value can carry more significant figures than the original spec. Whether it should is a different question: a mix design written as 150 lb/ft³ is a two significant figure convention, and 2,403 kg/m³ claims more precision than the input ever had.

More: lb/ft³ to g/cm³ · g/cm³ to kg/m³ · kg/m³ to lb/ft³ · Density Guide · Density

Related Unit Converters

lb/ft³ to g/cm³ g/cm³ to kg/m³ kg/m³ to lb/ft³ Density Conversion Guide Density Converters

Frequently Asked Questions

Why is the factor exactly 62.427961?

Because 1 g/cm³ is the density of water, and water's density in US customary units is 62.427961 lb/ft³. The number carries the 1959 pound and foot, cubed.

Do I multiply or divide for steel?

Steel is 7.85 g/cm³ in metric tables and about 490 lb/ft³ in US practice. Metric-to-US, multiply by 62.427961: 7.85 × 62.4 = 490. The 62.4 shortcut is accurate to 0.05%.

Why do US fabricators want lb/ft³?

Because plate weight is estimated as volume × density, and US shop practice works in inches and pounds. A 1-inch steel plate weighs 40.8 lb/ft² — derived from 490 ÷ 12.