# What’s the difference between density, specific density and true density?

Density or **mass density** (ρ) is the ratio between mass (m) and volume (V) of a sample which is expressed in the formula: ρ=m/V.

The most common units are kg/cm³ or g/cm³, whereas 1000k kg/m³ equal one g/cm³. The volume of a sample is depending on its temperature. Hence, the density is also **highly depending on the temperature**. Therefore, a precise measurement or regulation of the sample temperature is the key for precise results.

Besides the mass density we encounter the relative or specific density as well as the true or apparent density.

## Specific or relative density

The specific or relative density is used to simplify the comparison of measurements The density of the sample is compared with the density of a reference substance (often water) and the units are omitted.

## Real and apparent density

Depending on the measurement principle we either measure the real or the apparent density. The real density is the density of the sample in vacuum. Whereas the apparent density is density of the sample including the influence of the surrounding air. Consequently the apparent density measure about 1.2 kg/m³ too low. All Schmidt & Haensch density meters measure the real density.

**Typical applications:**

Dairy industry, Petro Chemicals, Polymers, Alcoholic Beverages, Cosmetic and Pharmaceutical Creams