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 |