# Specific Gravity Formula

Specific Gravity gives information about the weight and density of the object. It can be calculated by comparing the weight, mass and density of the given object with water of the same amount at 40C.

Specific Gravity Formula is expressed as

$Specific\;&space;gravity=\frac{Mass\;&space;of\;&space;unit\;&space;volume\;&space;of\;&space;the\;&space;substance}{Mass\;&space;of\;&space;unit\;&space;volume\;&space;of\;&space;water}$

or

$Specific\;&space;gravity=\frac{weight\;&space;of\;&space;the\;&space;substance}{Weight\;&space;of\;&space;the\;&space;equal\;amount\;&space;of\;&space;water}$

or

$Specific\;&space;gravity=\frac{Density\;&space;of\;&space;substance}{Density\;&space;of\;&space;equal\;volume\;&space;of\;&space;water}$

Specific gravity is a unitless measurement. The density of water is 1000 Kg/m3

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## Specific gravity Solved Examples

Problem 1: If the density of iron is 7850 kg/m3, what is its specific gravity?

Answer:

Given:

Density of iron = 7850 Kg/m3,
Density of water = 1000 Kg/m3

$Specific\;&space;gravity=\frac{Density\;&space;of\;&space;given\;substance}{Density\;&space;of\;&space;equal\;volume\;&space;of\;&space;water}$

$=\frac{7850}{1000}=7.85$

Problem 2: Compute the specific gravity if the density of granite is 174.8 lbs/ft3 and density of water is 62.4 lb/ft3?

Answer:

Known:

Density of granite = 174.8 lbs/ft3
Density of water = 62.4 lbs/ft3

$Specific\;&space;gravity=\frac{Density\;&space;of\;&space;given\;substance}{Density\;&space;of\;&space;equal\;volume\;&space;of\;&space;water}$

$=\frac{174}{62.4}=2.8$