lb/ft³ to g/cm³

1 lb/ft³ = 0.016018463374 g/cm³, and 1 g/cm³ = 62.4279605761 lb/ft³. The conversion is a single fixed factor: multiply lb/ft³ by 0.016018463374. Worked: 10 lb/ft³ = 0.16018463 g/cm³; 100 lb/ft³ = 1.60184634 g/cm³.

The US shop floor thinks in pounds per cubic foot: steel is 490, aluminum is 169. The international materials datasheet speaks g/cm³: steel is 7.85, aluminum is 2.70. The conversion is one division by 62.427961 — the density of water in US customary units.

By EnginStack Editorial Team | Reviewed against NIST, BIPM and primary-source documentation About →
lb/ft³
7.84904705 g/cm³
490 lb/ft³ = 7.84904705 g/cm³ 490 g/cm³ = 30,589.70068223 lb/ft³

Verified against NIST Special Publication 811 and BIPM SI definitions. The conversion factor is exact and traceable to the 1959 treaty constants.

lb/ft³ to g/cm³

The US shop floor thinks in pounds per cubic foot: steel is 490, aluminum is 169. The international materials datasheet speaks g/cm³: steel is 7.85, aluminum is 2.70. The conversion is one division by 62.427961 — the density of water in US customary units.

g/cm³ = lb/ft³ × 0.01601846327
1 lb/ft³ = 0.01601846327 g/cm³ — the reciprocal of 62.427961
The factor is exact — derived from SI definitions and the 1959 yard/pound agreement.

Worked Examples

Example 1: Convert a steel weight of 490 lb/ft³

490 × 0.01601846327 = 7.85 g/cm³

Example 2: Convert water at 62.4 lb/ft³

62.4 × 0.01601846327 = 1.000 g/cm³

Example 3: Convert aluminum at 168.6 lb/ft³

168.6 × 0.01601846327 = 2.70 g/cm³

Common lb/ft³ to g/cm³ Conversions

lb/ft³g/cm³Material / context
1 lb/ft³0.0160 g/cm³The definitional anchor.
62.4 lb/ft³1 g/cm³Water.
110 lb/ft³1.76 g/cm³Compacted soil.
168.6 lb/ft³2.7 g/cm³Aluminum.
490 lb/ft³7.85 g/cm³Carbon steel.
559 lb/ft³8.96 g/cm³Copper.

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 factor is the reciprocal of 62.427961, which is the density of water in US customary units. That gives a shortcut worth remembering: dividing a lb/ft³ figure by 62.427961 yields density relative to water, and density relative to water is numerically equal to g/cm³. Steel at 490 lb/ft³ divided by 62.4 is 7.85; no separate factor is needed. The same identity is why specific gravity, a pure ratio, can be read directly off a metric density scale, and why a soils report that states specific gravity needs no conversion at all.

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

Related Unit Converters

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

Frequently Asked Questions

Is 490 lb/ft³ steel or 489?

Structural steel is commonly specified at 490 lb/ft³ (about 7.85 g/cm³). The exact value varies slightly with alloy — carbon steel is about 7.83-7.87 g/cm³. For certified work use the alloy's exact value; for estimates, 490 is the industry standard.

How do I convert lb/ft³ to g/cm³ quickly?

Divide by 62.4: 150 ÷ 62.4 = 2.40 g/cm³ (concrete); 490 ÷ 62.4 = 7.85 g/cm³ (steel). The exact factor is 62.427961, making the shortcut accurate to 0.05%.

Why does the same material have two memorable numbers?

Each industry picked the unit that made its numbers round. Metric materials engineering got 2.7 for aluminum and 7.85 for steel in g/cm³. US construction got 169 and 490 in lb/ft³. The 62.4 bridge is exact.