National Physical Laboratory

Conversion Factors for Mass and Density (FAQ - Mass & Density)

Conversion Factors for Mass and Density

Historically there have been a variety of units of mass and density, and approximate conversion factors to some of these are given in Table 1 and Table 2 respectively. Exact conversions are shown in bold, others are quoted to seven significant figures.

Table 1: Some mass conversion factors from non-SI units

Unit Symbol Equivalent SI Value
grain gr             64.798 91 mg
metric carat CM            200.0 mg
ounce (avdp) oz         28.349 52 g
ounce (troy) (= 480 gr) oz tr         31.103 48 g
pound (avdp) lb        453.592 37 g
slug slug     14.593 90 kg
tonne t  1 000.0 kg
ton (= 2 240 lb) ton  1 016.047 kg

Table 2: Some density conversion factors from non-SI units

Unit Symbol Equivalent SI Value
pound per cubic foot lb·ft-3      16.018 46 kg·m-3
slug per cubic foot slug·ft-3     515.378 8 kg·m-3
pound per cubic inch lb·in-3  27 679.90 kg·m-3
Last Updated: 25 Mar 2010
Created: 9 Aug 2007