Convert lb/ft³ to kg/m³ Instantly
Use this Pounds per Cubic Foot to Kilograms per Cubic Meter converter to change density from lb/ft³ into kg/m³ with fast, accurate results. Enter any positive or zero density, use the reverse calculator when your value starts in kg/m³, or switch to the multi-unit tool for common engineering and material-density units.
Convert pounds per cubic foot to kilograms per cubic meter, reverse the calculation, compare common density units, or calculate density from mass and volume.
Enter density in lb/ft³ to calculate the equivalent density in kg/m³ and related units.
Use decimals when your material density is not a whole number.
Reverse the conversion by dividing kg/m³ by 16.01846337396014.
Start with one density unit and see equivalent values in metric and U.S. customary units.
Enter a mass and volume to calculate density, then view the result in lb/ft³ and kg/m³.
Converting pounds per cubic foot to kilograms per cubic meter means changing both the mass unit and the volume unit while keeping the physical density unchanged. Pounds per cubic foot, written as lb/ft³, is common in U.S. construction, material specifications, shipping, soil reports and bulk-product data. Kilograms per cubic meter, written as kg/m³, is the SI-style density unit widely used in engineering, science, concrete technology and international specifications.
For example, a material with a density of 10 lb/ft³ has a metric density of about 160.1846 kg/m³. A density of 100 lb/ft³ converts to about 1,601.8463 kg/m³. The numeric value becomes larger because one cubic meter contains many cubic feet, while kilograms and pounds also differ in size.
For manual work, multiply your lb/ft³ value by the conversion factor and keep enough decimal places for the accuracy your project needs. For repeated calculations, the converter above is faster and reduces the chance of copying the factor incorrectly.
The factor comes from combining an exact pound-to-kilogram relationship with an exact foot-to-meter relationship. A density unit is mass divided by volume, so the cubic-foot part must be converted as a volume, not as a simple length. This is why cubing the foot-to-meter relationship matters.
In practical terms, you do not need to repeat those steps every time. The combined factor 16.01846337396014 already includes both conversions. If you are documenting a technical workflow, it can be useful to state the factor and the number of decimal places retained so that another person can reproduce the result.
For authoritative background on SI mass and volume units, see the NIST guide to SI mass, the NIST guide to SI volume, and the NIST conversion-factor appendix.
The table below gives common lb/ft³ values and their approximate kg/m³ equivalents. It is wrapped in a responsive table container so it can scroll horizontally on narrow mobile screens without breaking the page layout.
| Pounds per Cubic Foot (lb/ft³) | Kilograms per Cubic Meter (kg/m³) | Pounds per Cubic Yard (lb/yd³) | kg/L |
|---|---|---|---|
| 1 | 16.0185 | 27 | 0.0160185 |
| 5 | 80.0923 | 135 | 0.0800923 |
| 10 | 160.1846 | 270 | 0.1601846 |
| 20 | 320.3693 | 540 | 0.3203693 |
| 40 | 640.7385 | 1,080 | 0.6407385 |
| 50 | 800.9232 | 1,350 | 0.8009232 |
| 60 | 961.1078 | 1,620 | 0.9611078 |
| 75 | 1,201.3848 | 2,025 | 1.2013848 |
| 100 | 1,601.8463 | 2,700 | 1.6018463 |
| 125 | 2,002.3079 | 3,375 | 2.0023079 |
| 145 | 2,322.6772 | 3,915 | 2.3226772 |
| 150 | 2,402.7695 | 4,050 | 2.4027695 |
| 200 | 3,203.6927 | 5,400 | 3.2036927 |
5 × 16.01846337396014 = 80.0923168698 kg/m³. Rounded to four decimals, the density is 80.0923 kg/m³.
50 × 16.01846337396014 = 800.923168698 kg/m³. This is approximately 800.9232 kg/m³.
100 × 16.01846337396014 = 1,601.846337396 kg/m³.
145 × 16.01846337396014 = approximately 2,322.6772 kg/m³.
Both units describe density, which is the amount of mass contained in a given volume. A higher number generally means more mass is packed into the same amount of space. Density is not the same as total weight or total mass. A small sample of a dense material can weigh less overall than a large volume of a light material, even though the dense material has a higher density value.
In construction and materials work, density can help with dead-load estimates, transport planning, storage calculations, mix design, quantity checks and comparisons between specifications written in different measurement systems. Engineers may also distinguish between true particle density, apparent density, bulk density, dry density, wet density, unit weight and specific gravity. Those terms are related but not always interchangeable, so use the exact definition required by your test method or specification.
The mass changes units and the reference volume changes from one cubic foot to one cubic meter, but the material's physical density is the same.
For the reverse calculation, divide the kg/m³ value by 16.01846337396014. You can also multiply by approximately 0.0624279605761. For example, 1,000 kg/m³ is about 62.4280 lb/ft³. The reverse calculator above applies the same relationship automatically.
If your workflow frequently moves between metric and U.S. customary data, keep one direction as the primary stored value and calculate the second unit from it. This helps prevent small differences caused by repeatedly converting rounded values back and forth.
A Pounds per Cubic Foot to Kilograms per Cubic Meter converter is useful anywhere density data comes from mixed standards or suppliers. In concrete and masonry work, a U.S. source may quote unit weight in lb/ft³ while an international specification or laboratory report uses kg/m³. Aggregate, sand, gravel, soil, insulation, timber, liquids, metals and manufactured products can also appear in either system.
Density conversion is especially helpful when estimating material mass from a known volume. Once density and volume use compatible units, mass can be calculated using mass = density × volume. The reverse is also true: if mass and volume are known, density = mass ÷ volume. Always check whether the listed value is bulk density, compacted density, loose density, dry density or another condition-specific measurement before using it for design or purchasing decisions.
In everyday construction language, people sometimes use density and unit weight loosely. Technically, density is mass per unit volume. Weight is a force and depends on gravity. Many U.S. construction tables nevertheless use pounds per cubic foot as a practical unit-weight or density-style value. If a project specification defines the term a particular way, follow that definition.
Bulk density includes the spaces between particles within a bulk material. That is why a loose aggregate, compacted aggregate and solid rock can have very different reported densities even when the mineral composition is similar. Moisture content can also change measured bulk density. A conversion calculator changes units only; it does not correct for moisture, compaction, temperature, grading or void content.
Changing pounds to kilograms but leaving cubic feet unchanged produces kg/ft³, not kg/m³.
Volume is cubic, so a cubic-foot conversion cannot be handled as though it were a one-dimensional length.
Carry additional digits through the calculation and round the final result to the precision required.
Density describes mass per volume. Total mass also depends on how much material you have.
Continue with related converters including Kilograms per Cubic Meter to Pounds per Cubic Foot, Kilograms per Cubic Meter to Pounds per Cubic Yard, Kilograms per Cubic Foot to Kilograms per Cubic Meter, Pounds per Cubic Yard to Tons per Cubic Yard, Tons per Cubic Yard to Pounds per Cubic Yard and Metric Tons per Cubic Meter to Kilograms per Cubic Meter.
These related pages are useful when material schedules, supplier documents, hauling estimates and engineering calculations use different mass-per-volume units. Convert to a common unit before comparing two materials so that the numbers are directly comparable.
Quick answers about lb/ft³, kg/m³ and density conversion.