Reference Information

Conversion Factors

 To convert metric (SI) unit Multiply by To obtain English unit Acceleration m/s2 3.281 ft/s2 Area cm2 m2 hectare (ha) = (100 m)2 0.1550 10.76 2.471 in2 ft2 acre = 43,560 ft2 Density kg/m3 = 10-3 g/cm3 0.001940 slug/ft3 Energy (work or quantity of heat) joule (J) = N·m kWh joule (J) = N·m 0.7376 2.650 x 106 0.0009480 ft·lb ft·lb Btu = 778 ft·lb Flowrate m3/s = (103 L/s) L/s = (10-3 m3/s) 35.31 15.85 cfs gpm Force newton (N) 0.2248 lb Kinematic viscosity m2/s = 104 St 10.76 ft2/s Length mm m km 0.03937 3.281 0.6215 in ft mile = 5,280 ft Mass kg 0.06854 slug Power watt (W) = J/s = N·m/s W 0.7375 0.001341 ft·lb/s lb/ft2 Pressure pascal (Pa) = N/m2 N/m2 0.0001450 0.02089 psi lb/ft2 Specific heat N·m/(kg·K) 5.981 ft·lb (slug·°R) Specific weight N/m3 0.006365 lb/ft3 Velocity m/s km/h 3.281 0.6215 fps mph Volume m3 liter (L) = (10-3 m3) 35.31 0.2642 ft3 U.S. gallon

Important Quantities

 SI unit English unit Acceleration of gravity 9.81 m/s2 32.2 ft/s2 Density of water (4°C, 39.4°F) 1,000 kg/m3 = 1.0 g/cm3 or 1.0 Mg/m3 1.94 slug/ft3 = 1.94 lb·sec2/ft4 Specific weight of water (15°C, 50°F) ~9810 N/m3 or 9.81 kN/m3 62.4 lb/ft3 Standard sea-level atmosphere 101.32 kN/m2, abs 760 mm Hg 10.33 m H2O 1013.2 millibars 14.7 psia 29.92 in. Hg 33.9 ft H2O