units & conversions

Preferred units:
length, m; mass kg; time, s; temperature, C; force, N; energy or work, J; power, W; pressure or stress, Pa
Preferred prefixes:
giga, G; mega, M; kilo k; milli, m; micro, mu;
Weight/mass units:
mass density is mass per unit volume, rho = [kg.m-3];
weight density or specific weight is force per unit volume, gamma = rho.g = [N.m-3]
relative density or specific gravity is the ratio of the substance density to density of water
Derivations:
K= 273 + C; N = kg.m.s-2; J = N.m; W = J/s; Pa = N.m-2;
Handy numbers:
1 m3 = 1000 l; 1 m water = 10 kPa; 2.3 ft water = 1 psi; 1 ft3 water= 62.4 lbs; 1 m3 water = 1000 kg
common distribution pressures: 150 ft = 45 m = 450 kPa = 65 psi;
For an excellent applet for converting any unit to (consistent) any other click here.
For another similar, longer table of conversion from any unit to (consistent)  click here.
USE THE FOLLOWING TABLE FOR CONVERTING SI UNITS TO U.S. CUSTOMARY UNITS
To convert from (SI) Conversion factor To get U.S. Customary
Length
Meters (m) Multiply by 3.28 Feet (ft)
Meters Multiply by 1.094 Yards
Meters per second (m/s) Multiply by 2.237 Miles per hour (mph)
Centimeters (cm) Multiply by 0.39 Inches (in.)
Milimeters (mm) Divide by 25.4 Inches
Kilometers (km) Divide by 1.608 Miles (mi)
m3/(m2-day) = m/day Multiply by 24.6 gpd/ft2
Area
cm2 Divide by 6.45 Square inch
m2 Multiply by 10.76 Square foot (ft2)
Hectare (ha = 10 000 m2) Multiply by 2.46 Acre
km2 ( = 100 ha = 106 m2) Multiply by 0.387 Square mile
Volume
Liters ( = 1 dm3) Divide by 28.3 Cubic foot (ft3)
m3 Multiply by 35.4 ft3
Liters Divide by 3.78 U.S. gal
Liters Divide by 4.54 Imp. gal
Liters/(s-ha) Multiply by 0.014 Inches/hour
m3 Divide by 3 780 Million U.S. gal (mg)
m3 Multiply by 8.54 Barrel
m3 Divide by 1 230 Acre-ft
Liters/s Divide by 43.75 Million gal/day (mgd)
Liters/s Multiply by 15.87 gal/min (gpm)
Liters/m2 Divide by 40.76 gal/ft2
Mass
Gram (g) Divide by 454 Pounds (lb)
Gram Multiply by 15.43 Grain
Kilogram (kg = 1 000 g) Multiply by 2.2 Pounds
Newton ( = 0.1 kgb) Multiply by 0.225 Pounds
Metric ton ( = 1 000 kg) Multiply by 1.1 U.S. ton
Metric ton Multiply by 0.98 English ton
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©1996-1999 William James

Last modified 97/02/03