Imperial / US Customary Units¶

Sources: NIST SP811 conversion tables. All values exact where the source definition is exact (marked), otherwise rounded to 7 significant figures.

† Affine unit (gauge pressure).

Area¶

Symbol	Name	SI unit	Factor to SI
`acre`	acre	`m^2`	4046.87
`ft2`	square foot	`m^2`	0.092903
`in2`	square inch	`m^2`	0.00064516
`mi2`	square mile	`m^2`	2.58999e+06
`yd2`	square yard	`m^2`	0.836127

Symbol	Name	SI unit	Factor to SI
`BTU_IT`	British thermal unit (International Table)	`J`	1055.06
`BTU_th`	British thermal unit (thermochemical)	`J`	1054.35
`ft_lbf`	foot pound-force	`J`	1.35582
`MMBtu`	million BTU (IT)	`J`	1.05506e+09

Symbol	Name	SI unit	Factor to SI
`ft`	foot	`m`	0.3048
`in`	inch	`m`	0.0254
`mi`	mile	`m`	1609.34
`mil`	mil (0.001 inch)	`m`	2.54e-05
`nmi`	nautical mile	`m`	1852
`yd`	yard	`m`	0.9144

Symbol	Name	SI unit	Factor to SI
`lb`	pound	`kg`	0.453592
`oz`	ounce	`kg`	0.0283495
`slug`	slug	`kg`	14.5939
`ton_long`	long ton (2240 lb)	`kg`	1016.05
`ton_short`	short ton (2000 lb)	`kg`	907.185

Symbol	Name	SI unit	Factor to SI
`ftH2O`	foot of water (conventional)	`Pa`	2989.07
`inH2O`	inch of water (conventional)	`Pa`	249.089
`inHg`	inch of mercury (conventional)	`Pa`	3386.39
`ksi`	kip per square inch	`Pa`	6.89476e+06
`psi`	pound per square inch	`Pa`	6894.76
`psia` †	pound per square inch (absolute)	`Pa`	6894.76
`psig` †	pound per square inch (gauge)	`Pa`	6894.76

Symbol	Name	SI unit	Factor to SI
`ft/min`	foot per minute	`m/s`	0.00508
`ft/s`	foot per second	`m/s`	0.3048
`kn`	knot	`m/s`	0.514444
`mph`	mile per hour	`m/s`	0.44704

Symbol	Name	SI unit	Factor to SI
`acre_ft`	acre-foot	`m^3`	1233.48
`bbl`	barrel	`m^3`	0.158987
`fl_oz`	fluid ounce (US)	`m^3`	2.95735e-05
`ft3`	cubic foot	`m^3`	0.0283168
`gal`	US gallon	`m^3`	0.00378541
`gal_imp`	Imperial gallon	`m^3`	0.00454609
`in3`	cubic inch	`m^3`	1.63871e-05
`Mbbl`	thousand barrels	`m^3`	158.987
`MMbbl`	million barrels	`m^3`	158987
`pt`	pint (US liquid)	`m^3`	0.000473177
`qt`	US quart	`m^3`	0.000946353
`yd3`	cubic yard	`m^3`	0.764555