Specific gravity is the density or ratio of any substance to another substance. It sometimes may be called just gravity or relative density. When calculating the specific gravity of a liquid or solid, water is normally the comparison (water has a specific gravity of 1).

Even though two objects are the same size, their density may be different. This is expressed in how much more weight the object is in comparison to the same amount of water. Likewise a gas is compared to air.

Specific Gravity of Gas

Click here to use our Specific Gravity of a Gas Mixture Calculator

Specific gravity of a gas is calculated as follows:

When density is known:

G=\frac{\rho_g}{\rho_a}

where

G gas gravity dimensionless
\rho_g density of the gas \frac{lb}{ft^3}
\rho_a density of air 0.075 \frac{lb}{ft^3}

When molecular weight is known:

G=\frac{M_g}{M_a}

where

G gas gravity dimensionless
M_g Molecular Weight of the gas
M_a Molecular Weight of air 28.9625

Conversion

Multiply Specific Gravity By To get
436995.7259 Grain Per Cubic Foot
252.8910451 Grain Per Cubic Inch
1 Gram Per Cubic Centimeter
1E+15 Gram Per Cubic Kilometer
1000000 Gram Per Cubic Meter
0.001 Gram Per Cubic Millimeter
1000000 Gram Per Kiloliter
1000 Gram Per Liter
1 Gram Per Milliliter
0.001 Kilogram Per Cubic Centimeter
1E+12 Kilogram Per Cubic Kilometer
1000 Kilogram Per Cubic Meter
1E-15 Kilogram Per Cubic Micrometer
0.000001 Kilogram Per Cubic Millimeter
998.8473734 Ounce Per Cubic Foot
0.578036674 Ounce Per Cubic Inch
62.42796084 Pound Per Cubic Foot
0.036127292 Pound Per Cubic Inch
1 Water ( Std. Conditions)
1 Specific Gravity, Water
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