Density Converter — kg/m³, g/cm³ and lb/ft³

Background.

Density describes mass per volume, but the same material value is written in very different-looking units across laboratories, engineering drawings, product data and customary specifications. A metric table may use kilograms per cubic metre, a chemistry source grams per cubic centimetre, and a construction schedule pounds per cubic foot. This converter preserves the physical density while changing that compound unit.

It is deliberately separate from the live density calculator. The solver uses density equals mass divided by volume to find an unknown quantity. This page begins with a density already known and changes only its unit. It also differs from a simple mass or volume conversion because both parts of the quotient must change together.

Kilograms per cubic metre is the canonical scale. One gram per cubic centimetre equals exactly 1,000 kg/m³: a gram is one thousandth of a kilogram, while a cubic centimetre is one millionth of a cubic metre, so dividing the two contributes a factor of one thousand. One kilogram per litre has the same value because a litre is exactly one cubic decimetre. One gram per litre equals one kg/m³.

Customary compound factors follow from exact international definitions. The pound is exactly 0.45359237 kg, the foot exactly 0.3048 m and the inch exactly 0.0254 m. Cubing the length is essential. One lb/ft³ is 0.45359237 divided by 0.3048 cubed, or 16.018463373960138 kg/m³. Forgetting to cube the length is the common error in hand calculations.

The page first multiplies the entered value by the source unit's kg/m³ factor, then divides by the target factor. The simultaneous breakdown shows every supported representation and makes order-of-magnitude mistakes visible. One lb/in³, for example, is 1,728 lb/ft³ because a cubic foot contains 12³ cubic inches—not merely twelve.

The worked comparison uses 1 g/cm³ and returns 1,000 kg/m³, 1 kg/L, 1,000 g/L and about 62.4279605761 lb/ft³. This is a unit anchor, not a promise that a specific sample of water has exactly that density. Water density varies with temperature, pressure, dissolved material and isotope composition.

Density cannot be negative, so negative input is rejected. Zero is retained as the mathematical boundary and is useful for checking a pipeline, although a physical vacuum is normally described through limits rather than a bulk material density. Decimal.js carries the exact base relationships and values round once at ten decimal places.

Do not use conversion to replace measurement conditions. Fuel, oil, soil, concrete and food products can have broad density ranges. Bulk density also differs from particle density because voids between particles count toward volume. A specification's stated temperature, moisture basis, compaction and test method travel with the number. Converting a catalogue figure does not make it representative of the batch in front of you; sampling and measurement still govern the engineering decision.

Symbols matter. `lb/ft³` is mass density in the customary shorthand used here; this page does not convert force density or specific weight. Specific gravity is dimensionless and compares a density with a reference, so it is not interchangeable with g/cm³ without stating the reference and conditions. Use the underlying density value when a mass-per-volume result is required.

What is density converter?

Density is mass divided by occupied volume. A density converter changes both the mass and cubed-length units while keeping that quotient physically equivalent. Kilograms per cubic metre is the coherent SI expression; g/cm³, kg/L and customary pound/volume forms are scaled representations of the same dimension.

How to use this calculator.

1. 01Enter the density value and the unit in which it is currently stated.
2. 02Choose the target compound unit.
3. 03Read the primary conversion and compare the simultaneous kg/m³ and g/cm³ anchors.
4. 04Keep the source material's temperature, moisture and test conditions with the converted number.
5. 05Use the density solver instead if mass or volume, rather than the unit, is unknown.

The formula.

Assign each supported unit its kilograms-per-cubic-metre value. Multiply by the source factor to reach the canonical value and divide by the target factor. The customary factors are derived from exact pound and length definitions, with the length factor cubed.

For 1 g/cm³, canonical density is 1×1000 = 1000 kg/m³. Divide by 16.018463373960138 to obtain 62.4279605761 lb/ft³ after the single output rounding. Decimal.js performs every multiplication and division.

A worked example.

Frequently asked questions.

References& sources.

1. [1]NIST SP 811 Appendix B supplies the exact mass, length, volume and customary conversion definitions.
2. [2]BIPM SI Brochure defines kilogram and metre and accepts the litre as one cubic decimetre.
3. [3]NIST SP 330 independently documents SI derived-unit construction and litre usage.
4. [4]NIST Handbook 44 Appendix C provides customary/SI relationships for legal metrology.
5. [5]BIPM Measurement Units provides the current SI definition framework.