Density converter
Convert one density value across common metric and U.S. customary units in real time.
Density inputs
Converted density
Conversion table
| Unit | Symbol | Converted value |
|---|---|---|
| Kilograms per cubic decimeter | kg/dm³ | 1 |
| Kilograms per cubic meter | kg/m³ | 1,000 |
| Pounds per cubic foot | lb/ft³ | 62.427961 |
| Pounds per cubic yard | lb/yd³ | 1,685.554935 |
| Pounds per US gallon | lb/US gal | 8.345404 |
All rows represent the same mass density. Differences are caused only by the unit scale.
How to use the density converter
What this calculator does
This calculator expresses one mass density in five equivalent units: Kilograms per cubic decimeter, Kilograms per cubic meter, Pounds per cubic foot, Pounds per cubic yard, and Pounds per US gallon. Mass density is mass divided by volume, commonly written as ρ = m/V. The tool performs exact unit scaling from one canonical SI value; it does not estimate the density of an unknown material or adjust for temperature, pressure, moisture, packing, or composition. For the formal quantity definition and SI unit, see the NIST Guide to the SI section on mass density.
When to use it
Use the converter when a laboratory specification is written in kg/m³ but an engineering worksheet uses lb/ft³, when bulk aggregate is quoted in lb/yd³, when a liquid product sheet lists lb/US gal, or when a familiar g/cm³-style value needs to be compared with SI data. It is also useful for checking that two supplier documents describe the same material property despite using different units.
How to calculate
- The calculator opens with a ready-to-use example of 1 kg/dm³, equal to 1,000 kg/m³. The matching Excel workbook is immediately available.
- Replace any one displayed value. As soon as the entry is valid, every other field, result card, summary pill, table row, and workbook source updates from the same canonical density.
- Read SI density for the primary kg/m³ result, then use the four secondary cards or the conversion table for alternative units.
- Select Download Excel to create a current-state OOXML workbook containing Summary and Inputs sheets. Select Reset to clear all five density values. Reset also removes the calculated output and disables export until a complete valid value is entered again.
Input guide
Kilograms per cubic decimeter accepts a required nonnegative decimal such as 1. It is numerically identical to g/cm³ because one kilogram per cubic decimeter equals one gram per cubic centimeter. A higher value raises every converted result proportionally. Do not type unit symbols into the field. Kilograms per cubic meter accepts a required nonnegative decimal such as 1000 and is the SI expression. The BIPM SI Brochure lists kg/m³ as the coherent SI unit for mass density.
Pounds per cubic foot accepts a required nonnegative decimal such as 62.427961. It is often used for construction materials and fluids in U.S. engineering. Pounds per cubic yard accepts a required nonnegative decimal such as 1685.554935; because a cubic yard contains 27 cubic feet, the numerical value is 27 times the lb/ft³ value. Pounds per US gallon accepts a required nonnegative decimal such as 8.345404 and specifically uses the U.S. liquid gallon. Do not substitute an Imperial gallon value. Every field uses an en-US decimal point; grouped thousands with commas are accepted only in standard three-digit groups. Scientific notation, decimal commas, negative values, and mixed text are rejected visibly.
Output guide
SI density is the primary result in kg/m³. Metric compact repeats the equivalent kg/dm³ value. The three customary output cards report Pounds per cubic foot, Pounds per cubic yard, and Pounds per US gallon. The summary pills identify the most recently edited source unit, repeat the SI value, and show the U.S.-gallon conversion. In the Conversion table, Unit gives the full unit name, Symbol gives the compact notation, and Converted value gives the current equivalent number. Zero means a zero mass-per-volume ratio; large values simply indicate greater mass packed into the same volume. These are exact conversion identities subject only to display rounding, not recommendations or measured material properties.
Worked example
The startup example begins with 1 kg/dm³. Since 1 dm³ is 0.001 m³, the same mass distributed through one cubic meter is 1 ÷ 0.001 = 1,000 kg/m³. Multiplying 1,000 kg/m³ by the exact unit factors produces 62.427961 lb/ft³, 1,685.554935 lb/yd³, and 8.345404 lb/US gal at the displayed precision. These figures match the first-open cards, table, live summary, and workbook checkpoints.
How density conversion works
The calculator first converts the edited field to kilograms per cubic meter. It then derives every other unit from that single canonical value. This architecture prevents chained rounding, where one displayed result is converted again and small errors accumulate. For example, lb/yd³ is calculated directly from kg/m³ rather than by multiplying the rounded lb/ft³ display. NIST publishes authoritative SI conversion-factor guidance, and its unit-style checklist illustrates preferred forms such as kg/m³.
Practical interpretation and common mistakes
Density depends on the physical state and conditions of a sample. Temperature can change liquid density, pressure strongly affects gases, and bulk materials may vary with moisture and compaction. Therefore, a unit conversion preserves the stated number's physical meaning but cannot improve the quality of the underlying measurement. Keep the source conditions with the converted value whenever they matter.
The most common mistakes are confusing mass density with specific gravity, mixing U.S. and Imperial gallons, treating kg/dm³ as kg/m³, or copying a rounded intermediate into another calculation. The SI unit of volume is the cubic meter, while the liter is accepted for use with SI; NIST's SI volume guidance explains the relationship between cubic meters, cubic decimeters, and liters.