# Specific Gravity

on . Posted in Dimensionless Numbers

Specific gravity, abbreviated as SG, a dimensionless number, 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.  The density of the substance and the density of water must be measured using the same units of mass and volume for accurate comparison.  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 Index

The specific gravity of a substance is determined by comparing its density to the density of water at a specified temperature and pressure.  By definition, the specific gravity of water is 1.  Therefore, if the specific gravity of a substance is less than 1, it is less dense than water, and if it is greater than 1, it is denser than water.

For example, in the context of minerals and ores, specific gravity is often used to determine the mineral composition and to assess the concentration of valuable components.  In the petroleum industry, specific gravity is used to classify and measure the density of crude oil and other hydrocarbon liquids.  It's important to note that specific gravity is temperature dependent because the density of both the substance and water can vary with temperature.  Therefore, when specific gravity is specified, the temperature at which it is measured should be indicated.

### Specific gravity formula

$$SG \;=\; \rho_s \;/\; \rho_r$$     (Specific Gravity)

$$\rho_s \;=\; SG \; \rho_w$$

$$\rho_w \;=\; \rho_s \;/\; SG$$

### Solve for SG

 density of substance, ρs density of reference, ρw

### Solve for ρs

 specific gravity, SG density of reference, ρw

### Solve for ρw

 density of substance, ρs specific gravity, SG

Symbol English Metric
$$SG$$ = specific gravity of material (water = 1) $$dimensionless$$
$$\rho_s$$  (Greek symbol rho) = density of substance $$lb \;/\; ft^3$$ $$kg \;/\; m^3$$
$$\rho_w$$  (Greek symbol rho) = density of reference $$lb \;/\; ft^3$$ $$kg \;/\; m^3$$

• This is a Density Conversion

### Specific Gravity conversion table

Multiply By To Get
436,995.7259 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
1,000,000 gram per kiloliter
1,000 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 standard conditions
1 specific gravity, water

### Specific Gravity of material

Material Specific Gravity
Acetylene 0.0017
Air, dry 0.0013
Alcohol 0.82
Aluminium 2.70
Aluminium Alloy 356.0 2.68
Aluminium Alloy 360.0 2.68
Aluminium Alloy 364.0 2.63
Ammonia Vapor 0.60
Antimony 6.68
Balsa Wood 0.2
Barium 3.62
Barium sulfate 4.5
Boron 2.34
Brass 8.48
Calcium sulfate 2.96
Carbon 2.26
Carbon dioxide 0.00198
Carbon monoxide 0.00126
Cast iron 7.20
Caustic potash 2-044
Cement 3.15
Cerium 6.77
Cesium 1.873
Chromium 7.03
Citric acid 1.665
Clay 2.6
Copper 8.96
Depleted uranium 19.1
Diesel fuel 0.84
Epoxy resin 1.8 - 2.0
Ethanol 0.78
Gasoline 0.70 - 0.76
Glass 2.40 - 2.70
Gold 19.30
Grease 0.92 - 0.94
Hematite 5.26
Hydrogen 0.00009
Iron 7.87
Limestone 2.8
Melamine 1.8 - 2.0
Mercury 13.56
Natural Gas 0.59
Nickel 8.9
Nylon 1.12
Oak wood 0.75
Osmium 22.59
Oxygen 0.00143
Parrafin 0.80
Petrol (gasoline) 0.72
Phenolic 1.75 - 1.95
Platinum 21.5
Polyester 1.35 - 2.3
Polyurethane 1.11 - 1.25
Propane gas 1.55
PVC 1.36
Pyrite 5.02
Quartz 2.65
Rubber 0.96
Salt 2.165
Silicon 2.33
Soda ash 2.53
Sodium bicarbonate 2.16
Sodium sulfite 2.63
Steel, carbon 7.82
Steel, cold drawn 7.83
Steel, machine 7.80
Strontium 2.64
Sulfur 2.07
Table Salt 2.17
Tantalum 16.69
Tellurium 6.24
Terbium 8.27
Thallium 11.85
Thulium 9.32
Tin, pure 7.28
Titanium 4.506
Titanium dioxide, Anatase 3.77
Tungsten 19.25
Tungsten, carbide 14.29
Uranium 18.7
Water 1
Water, sea salt 1.027
Ytterbium 6.97
Yttrium 4.47
Zinc 7.12
Zirconium 6.506
Zirconium silicate 3.85