Density Converter

Density is the mass of a substance packed into a given volume — how "heavy" a material is for its size. It's one of the most widely used physical properties in science and engineering, determining whether an object floats or sinks, how materials are classified and priced, and how structural and fluid systems behave under load.

Our Density converter supports 42 units drawn from several different measurement conventions. The core SI units — kilogram/cubic meter (the SI derived unit), gram/cubic centimeter, and gram/cubic meter — are what you'll find in physics and chemistry references; water, for example, has a density of 1,000 kg/m³, equal to exactly 1 g/cm³. A large family of metric mass-per-liter units is also included, from exagram/liter and petagram/liter down to femtogram/liter and attogram/liter, covering everything from industrial bulk-material densities to trace concentrations measured in laboratories.

For imperial and US customary work, the converter handles pound/cubic inch, pound/cubic foot, pound/cubic yard, pound/gallon (both US and UK gallons, which differ in size), ounce/cubic inch, ounce/cubic foot, ounce/gallon, and grain-based units per gallon or cubic foot — the units commonly seen in US engineering drawings, material specifications, and shipping documentation. Specialized entries like ton (short)/cubic yard, ton (long)/cubic yard, slug/cubic foot (the density unit paired with the slug, the imperial unit of mass used in some engineering calculations), psi/1000 feet (a drilling-fluid density convention used in the oil and gas industry), and Earth's mean density (5,518 kg/m³) round out the list.

To convert, choose your starting unit and target unit from the dropdown lists and enter a value — the result is calculated instantly to up to 12 significant digits. For example, converting water's density of 1,000 kg/m³ to pounds per cubic foot gives about 62.43 lb/ft³, a figure widely used in US civil and structural engineering.

Density values are also the basis for specific gravity (a substance's density relative to water) and for the Specific Volume converter elsewhere in this Engineering Converters section, since specific volume is simply the mathematical inverse of density. Keeping a precise, correctly-unit-tagged density figure on hand makes both of those follow-on calculations straightforward rather than a source of unit-mismatch errors.

Density conversions are essential in materials science (comparing metals, plastics, and composites by density-to-strength ratio), civil and structural engineering (calculating dead loads from material densities), naval architecture and fluid mechanics (buoyancy and displacement calculations), chemistry and process engineering (converting concentration and solution density between unit systems), and international trade, where US customary densities must be converted to metric for shipping manifests and product specifications.

Every conversion factor in this tool is drawn from standard, internationally recognized definitions of mass and volume units, so results are consistent with the values used in engineering handbooks, materials databases, and scientific references. The converter is free, requires no account, and works smoothly on both desktop and mobile.