Conversion Factors Length 1 inch = 25.4 mm Area 1 square inch = 6.4516 cm2 1 foot = 0.3048 m 1 square foot = 9.290 304 dm2 1 yard = 0.9144 m 1 square yard = 0.836 127 4 m2 1 mile = 1.609 344 km 1 acre = 0.404 685 6 ha 1 nautical mile = 1.853 km 1 square mile = 2.589 988 km2 1 millimetre = 0.03937 inch 1 square centimetre = 0.1550 in2 1 centimetre = 0.3937 inch 1 square metre = 1.1960 yd2 1 metre = 1.0936 yard 1 hectare = 2.4711 acres 1 kilometre = 0.6214 mile 1 square kilometre = 0.3861 mile2 Volume 1 cubic inch = 16.387 064 cm3 Mass 1 ounce (437.5 grain) = 28.349 523 g 1 cubic foot = 28.316 85 dm3 1 pound = 0.453 592 37 kg 1 cubic yard = 0.764 555 m3 1 stone (14 lb) =   6.3503 kg 1 Imperial fluid ounce = 28.413 062 mL 1 hundredweight (112 lb) = 50.802 kg 1 Imperial pint = 0.5683 L 1 short ton (2000 lb) = 907.184 74 kg 1 Imperial gallon = 4.546 090 L 1 long ton (UK) = 1.016 tonne 1 US ounce = 29.574 mL 1 milligram = 0.0154 grain 1 US pint = 0.4731 L 1 gram = 0.0353 oz 1 US gallon = 3.7854 L 1 kilogram = 2.2046 lb 1 cubic centimetre = 0.0610 in3 1 tonne = 0.9842 ton 1 cubic decimetre = 0.0353 ft3 1 cubic metre = 1.3080 yd3 Power 1 hosepower (mechanical) = 745.6999 W 1 litre = 1.76 Imperial pint 1 horsepower (electrical) = 746 W 1 hectolitre = 21.997 Imperial gallons Speed 1 mile / hour = 0.44704 m/s Force 1 pound-force = 4.448 222 N = 1.609 344 km/h 1 kilogram-force = 9.80665 N Pressure 1 lb-force / inch2 (psi) = 6.894757 kPa Energy 1 British Thermal Unit (BTU) = 1055.06 J 1 inch of Hg = 3.38639 kPa 1 Foot pound-force = 1.355818 J 1 mm of Hg = 133.322 Pa 1 calorie = 4.1868 J 1 stan. atmosphere (atm) = 101.325 kPa 1 kilowatt hour = 3.6 MJ