Metal Density and Specific Gravity Chart — Steel, Aluminum, Iron, Zinc and More

Metal density is the mass of a material in a given volume. It helps estimate the weight of a plate, bar, casting, or other part when a drawing gives dimensions but not mass. This chart gives approximate reference values for selected metals and metal materials. Pure-element values are labeled as such, and alloy values are identified by type or grade. Actual density can vary with composition, product form, porosity, and temperature, so use the material specification for a final estimate.

Metal density and specific gravity chart

The values below use kilograms per cubic metre (kg/m³) as the primary density unit. Specific gravity is shown as an approximate ratio to water using the engineering reference convention of 1,000 kg/m³.

What specific gravity means

Specific gravity is the ratio between a material’s density and the density of a reference substance, usually water. It has no units. With the common 1,000 kg/m³ water convention, divide a material’s density in kg/m³ by 1,000 to get an approximate specific gravity. This is why a metal with a density near 7,850 kg/m³ has a specific gravity near 7.85.

The ratio depends on the chosen water reference and temperature. It is not a universal identity between specific gravity and density in g/cm³. Small differences between published values can also reflect rounding, material composition, or measurement conditions. The chart keeps its conversions consistent with the stated 1,000 kg/m³ convention.

Why material form and grade matter

“Steel,” “aluminum,” and “cast iron” describe broad material families rather than one fixed composition. A general mild-steel value is useful for an early estimate, but it does not identify a grade such as A36 or 1045. Stainless steel also varies by grade, so use the exact grade rather than assuming that a general steel value applies.

Aluminum alloys are not interchangeable with elemental aluminum. Casting composition and porosity can affect a casting’s bulk density, while wrought alloys have their own published values. Cast iron varies by grade and graphite structure. Likewise, a value for elemental zinc does not specify a zinc casting alloy or sheet product. The nickel value is an elemental reference and should not be treated as a cast or rolled nickel product value.

These distinctions are why the table labels elemental references and named materials explicitly. Where a broad label would hide meaningful variation, use the exact grade and condition from the drawing, purchase specification, or material certificate and consult the supplier’s data.

Converting metal density units

To convert density from g/cm³ to kg/m³, multiply by 1,000. To convert from kg/m³ to g/cm³, divide by 1,000. For example, 7.86 g/cm³ equals 7,860 kg/m³. These conversions change units only; they do not change the material value or add precision that the source did not provide.

Density is mass per volume. It is different from specific weight, which is force per volume and is commonly expressed in N/m³. For mass estimates, use density with volume and keep the units consistent.

Worked example: estimate a steel plate’s mass

Consider a rectangular plate that is 1,000 mm long, 500 mm wide, and 2 mm thick. Its volume is 1,000 × 500 × 2 = 1,000,000 mm³, or 0.001 m³. Using an explicitly assumed planning density of 7,860 kg/m³, the estimated mass is 7,860 × 0.001 = 7.86 kg. This assumes a solid rectangular plate and ignores holes, cut-outs, coatings, and manufacturing tolerances.

For other shapes, use Mechanitec’s Metal Weight Calculator, which estimates mass from the selected material and dimensions. Check the selected density and geometry against the actual specification before ordering or releasing a design.

Limits of a density estimate

Reference values are suitable for preliminary calculations, comparisons, and estimates. They do not establish mechanical strength, stiffness, fatigue life, joint capacity, or safe load. A material’s alloy, temper, heat treatment, and manufacturing route matter to those properties. Cast parts may also contain porosity or have geometry that differs from the ideal solid shape used in a simple volume calculation.

For a production weight, shipping declaration, lifting plan, or safety-critical calculation, verify the exact grade and product condition with the manufacturer or material certificate. If a measured component differs from the estimate, first check the actual dimensions, internal features, coatings, and material identification.

Sources and method

Elemental reference values are sourced from NIST’s X-ray material table and cross-checked against the NIST Center for Neutron Research table at 295 K and PubChem’s elemental density table. References round differently: for example, the Canadian Conservation Institute (CCI) lists lead at 11.33 g/cm³ and gold at 19.30 g/cm³, while this chart uses 11.35 and 19.32 g/cm³ from its cited elemental source. Treat those as approximate reference values, not certified material properties.

For steel, CCI lists carbon steel at 7.86 g/cm³; a mild-steel tube supplier gives 7.85 g/cm³. The chart uses 7.86 as a planning value. Its 7.15 g/cm³ gray cast iron reference is reported by NORAMARK and MatWeb for ASTM A48 Class 40 gray cast iron; CCI lists 7.20 g/cm³ for generic gray cast iron, illustrating the difference between material references. Metric conversions retain the displayed precision, and specific gravity uses the approximate 1,000 kg/m³ water convention.