Specific gravity

Specific Gravity (SG) is a special case of relative density.

It is defined as the ratio of the density of a given substance, to the density of water (H₂O). Substances with a specific gravity greater than 1 are heavier than water, and those with a specific gravity of less than 1 are lighter than water.

${\mbox{SG}}={\frac {\rho _{\mathrm {substance} }}{\rho _{\mathrm {H2O} }}}$ ^[1]

SG is by definition dimensionless and therefore not dependent on the system of units used (e.g. slugsft⁻³ or kgm⁻³), assuming that the units are consistent. Based on the SG-value of a given substance, the density of that substance can be calculated.

Related pages[change | change source]

Other websites[change | change source]

Specific Gravity Calculator Archived 2022-09-14 at the Wayback Machine

References[change | change source]

↑ The density of the denominator, or reference, is $\rho _{\mathrm {H2O} }$ = 1000kgm^-3 (at 4°C/39.2°F) in SI units.

Fundamentals of Fluid Mechanics Wiley, B.R. Munson, D.F. Young & T.H. Okishi
Introduction to Fluid Mechanics Fourth Edition, Wiley, SI Version, R.W. Fox & A.T. McDonald
Thermodynamics: An Engineering Approach Second Edition, McGraw-Hill, International Edition, Y.A. Cengel & M.A. Boles

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[1] The density of the denominator, or reference, is $\rho _{\mathrm {H2O} }$ = 1000kgm^-3 (at 4°C/39.2°F) in SI units.

[1]