View source for Specific gravity

{{onesource|date=April 2025}}
'''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 (H<sub>2</sub>O). 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.

<math>\mbox{SG} = \frac{\rho_\mathrm{substance}}{\rho_\mathrm{H2O} }</math>
<ref>The density of the denominator, or reference, is <math>\rho_\mathrm{H2O}</math> = 1000kgm<sup>-3</sup> (at 4°C/39.2°F) in SI units.</ref>

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

== Specific Gravity Media ==
<gallery widths='160px' heights='100%' mode='traditional' caption=''>
File:US Navy 111005-N-ZN781-031 Aviation Boatswain's Mate (Fuel) 3rd Class Rolando Calilung tests for a specific gravity test on JP-5 fuel.jpg|A [[United States Navy]] [[Aviation boatswain's mate]] tests the specific gravity of [[JP-5]] fuel

File:PycnometerEmpty.jpg|An empty glass pycnometer and stopper

File:Pycnometer full.jpg|A full pycnometer, photographed on 5 mm squares.
</gallery>
== Related pages ==
* [[Buoyancy]]
* [[Fluid mechanics]]
* [[Relative density]]
== Other websites ==
* [https://calculator1.net/physics/specific-gravity-calculator Specific Gravity Calculator] {{Webarchive|url=https://web.archive.org/web/20220914064129/https://calculator1.net/physics/specific-gravity-calculator |date=2022-09-14 }}
== References ==
<references/>
* ''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


{{physics-stub}}

[[Category:Physics]]