kg/m³ to lb/ft³

1 kg/m³ = 0.0624279605761 lb/ft³, and 1 lb/ft³ = 16.018463374 kg/m³. The conversion is a single fixed factor: multiply kg/m³ by 0.0624279605761. Worked: 10 kg/m³ = 0.62427961 lb/ft³; 100 kg/m³ = 6.24279606 lb/ft³.

Every US concrete mix design lives on this conversion. Water is 62.4 lb/ft³. Normal-weight concrete is about 150 lb/ft³. A metric spec sheet says 2,400 kg/m³; the US batch plant wants 150 lb/ft³. The bridge is 16.018463 — the 1959 pound divided by the 1959 foot, cubed.

By EnginStack Editorial Team | Reviewed against NIST, BIPM and primary-source documentation About →
kg/m³
62.42796058 lb/ft³
1,000 kg/m³ = 62.42796058 lb/ft³ 1,000 lb/ft³ = 16,018.46337397 kg/m³

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.

kg/m³ to lb/ft³

Every US concrete mix design lives on this conversion. Water is 62.4 lb/ft³. Normal-weight concrete is about 150 lb/ft³. A metric spec sheet says 2,400 kg/m³; the US batch plant wants 150 lb/ft³. The bridge is 16.018463 — the 1959 pound divided by the 1959 foot, cubed.

lb/ft³ = kg/m³ × 0.06242796059
1 kg/m³ = 0.06242796059 lb/ft³ — the 1959 pound over the 1959 foot, cubed
The factor is exact — derived from SI definitions and the 1959 yard/pound agreement.

Worked Examples

Example 1: Convert a 2,400 kg/m³ concrete mix

2,400 × 0.06242796059 = 149.8 lb/ft³

Example 2: Convert steel at 7,850 kg/m³

7,850 × 0.06242796059 = 490.1 lb/ft³

Example 3: Convert water at 1,000 kg/m³

1,000 × 0.06242796059 = 62.43 lb/ft³

Common kg/m³ to lb/ft³ Conversions

kg/m³lb/ft³Material / context
1 kg/m³0.0624 lb/ft³The definitional anchor.
1.225 kg/m³0.0765 lb/ft³Air at sea level.
600 kg/m³37.5 lb/ft³Dry pine wood.
1,000 kg/m³62.4 lb/ft³Water — the US construction anchor.
1,600 kg/m³99.9 lb/ft³Lightweight concrete.
2,400 kg/m³149.8 lb/ft³Normal concrete.
7,850 kg/m³490 lb/ft³Carbon steel.

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.

This direction is what a metric design package needs when the concrete is placed by a US plant, and the round numbers on both sides are a trap. A metric mix design reads 2,400 kg/m³; the US equivalent reads 150 pcf; the exact conversion gives 149.8, not 150. Both conventions are nominal values chosen for convenience, and both are routinely exceeded or missed in the field, so the 0.2 difference is not an error to chase. What does matter is consistency: if a dead-load calculation uses 150 and the supplier invoices against 2,400, the two documents describe concretes that differ by 0.13 percent.

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

Related Unit Converters

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

Frequently Asked Questions

Why is water 62.4 lb/ft³?

Because a cubic foot of water weighs 62.4 pounds — a consequence of the 1959 pound and foot definitions, cubed. The exact value is 62.427961 lb/ft³ at maximum density. US engineers memorize 62.4 the way metric engineers memorize 1,000; both are the same water.

Is concrete really 150 lb/ft³?

Normal-weight concrete is commonly specified at 150 lb/ft³ (about 2,400 kg/m³). Lightweight concrete drops to 90-115 lb/ft³, and the mix density is a structural input — changing it changes the dead load and the footing size.

What about the 1959 foot?

The foot was defined as exactly 0.3048 meters by the 1959 agreement. Density cubes it: one cubic foot is exactly 0.028316846592 cubic meters. That's where the 16.018463 comes from.