# Specific Gravity Definition

In physics, **specific gravity** relates to the substance's densities and water at a precise temperature. It is also called **relative gravity**. In simple words, specific gravity can also be defined as the **ratio** between the **substance** and **water densities**. Because the specific gravity has no unit, it is dimensionless. Densities are canceled out in a formula when they're expressed as weight per volume, and density units cancel out.

**Table of Contents**

## Formula of Specific Gravity

If you want to calculate specific gravity, you can use the formula listed below or jump to our calculator to find your answer instantly.

SG = ρ substance / ρ H_{2}O

**Where,**

SG = Specific Gravity

ρ substance = density of a substance

ρ H_{2}O = density of water

**Note:**

To know how to find out the specific gravity, you can use our Specific Gravity Calculator.

### Example

For a more precise understanding of how to find the specific gravity, let us have an example below:

Suppose the density of gasoline is 810 kg/m^{3}. Then find out the specific gravity of the gas.

**Given data**

The density of gasoline = 810 kg/m^{3}

The density of water = 1000 kg/m^{3}

**To Find**

The specific gravity of gas = ?

**Solution**

To find the specific gravity of gas, you can use the formula listed below:

SG = ρ substance / ρ H_{2}O

Putting values in the formula:

SG = 810 / 1000 = 0.81