What is the conversion factor from lb/ft³ to kg/m³?

The exact factor is 16.01846337. This is derived from the definitions: 1 pound = 0.45359237 kg and 1 foot = 0.3048 m, so 1 lb/ft³ = 0.45359237 / (0.3048)³ kg/m³ ≈ 16.01846337 kg/m³.

What is water density in lb/ft³?

Pure water at 4 °C (maximum density) is 62.428 lb/ft³, which equals 1000 kg/m³. At room temperature (20 °C) water is about 62.316 lb/ft³ (998.2 kg/m³).

Why do engineers use both lb/ft³ and kg/m³?

US construction, timber, and HVAC industries traditionally use lb/ft³, while most of the world and international scientific literature uses SI units (kg/m³). Engineers often need to convert when working with mixed-unit project documents or international datasheets.

How dense is concrete in kg/m³?

Normal-weight concrete is typically 143–150 lb/ft³, which converts to about 2,290–2,400 kg/m³. Lightweight concrete ranges from 90–115 lb/ft³ (1,440–1,840 kg/m³).

Can I convert kg/m³ back to lb/ft³?

Yes — multiply kg/m³ by 0.0624279606 to get lb/ft³. This tool supports reverse conversion: just type in the kg/m³ field and the lb/ft³ result appears automatically.

lb/ft3 to kg/m3 Converter

Enter a density in lb/ft³ and instantly get kilograms per cubic meter, with a reference table of common material densities.

Density Conversion

lb/ft³ (pounds per cubic foot)

kg/m³ (kilograms per cubic meter)

Formula: kg/m³ = lb/ft³ × 16.01846337

Common Material Densities

Click a row to load that density into the converter.

Material	lb/ft³	kg/m³

Copied!

Summary

This converter translates density values from pounds per cubic foot (lb/ft³) — common in US construction and engineering — to kilograms per cubic meter (kg/m³), the SI standard unit. The exact conversion factor is 1 lb/ft³ = 16.01846337 kg/m³. Enter a value in either direction for an instant result, then check the reference table for densities of everyday materials.

How it works

Enter a density in the lb/ft³ field; the kg/m³ result appears instantly.
Or type in the kg/m³ field to convert back to lb/ft³.
The tool multiplies lb/ft³ by 16.01846337 to get kg/m³.
Click any row in the reference table to load that material's density.
Copy either result with one click using the copy button.

Use cases

Convert US timber density from lb/ft³ to metric specs for international suppliers.
Translate HVAC insulation density values from imperial datasheets into SI units.
Convert concrete density for metric-unit structural engineering reports.
Verify soil bulk density figures when switching between imperial and metric software.
Prepare fluid density inputs in kg/m³ from lb/ft³ measurements for simulation tools.
Reconcile material specs that mix lb/ft³ and kg/m³ in multi-region projects.

Frequently Asked Questions

Last updated: 2026-09-09 · Reviewed by Nham Vu