UnitsIQ is efunda's iPhone version of its online unit conversion utilities. It features 927 scientific and engineering units in 78 categories, including hardness, wire, and sheet metal gage units. App Store
Rigorously speaking, specific gravity is a dimensionless unit. Also called relative density, it is the ratio of the density of a substance to that of a standard substance, usually water at 4°C. For ease of conversion, we took the liberty of assigning the specific gravity a density unit so it can be easily related to regular density units. This conversion table assumes water at 4°C as the standard substance.