Units
Length
Mass
Weight, Force
Torque, Moment
Gravity
English
Inches (in, ), feet (ft, )
Metric (SI)
Millimeters (mm), centimeters (cm),
meters (m)
Kilograms, (kg)
Newtons, (N)
Newton-meter, (N-m)
Newton-millimeter, (N-mm)
9.81 m/s2
Pounds, (lbm)
Pounds, (lbf)
Inch-pound, (in-lbf)
Foot-pound, (ft-lbf)
32.2 ft/sec2
386 in/sec2
Conversions
Length
Weight, Force
Length
Mass
Weight, Force
English
1 ft = 12 in
1 mile = 5280 ft
1 kip (kilopound) = 1,000 lbf
= 1x103 lbf
1 ton = 2,000 lbf = 2x103 lbf
English to Metric
1 in = 2.54 cm = 25.4 mm
1 ft = 0.3048 m
1 lbm = 0.454 kg
1 slug = 14.5938 kg
1 lbf = 4.4482 N
Mass and Weight Relations
W = mg
Metric (SI)
1 meter = 1,000 mm.
1 meter = 100 cm.
1 kilometer = 1x103 m
1 kilometer = 1x106 mm
1 kN (kiloNewton) = 1x103 N
Metric to English
1 cm = 0.3937 in
1 m = 39.37 in
1 m = 3.28 ft
1 kg = 2.2 lbm
1 N = 0.2248 lbf
W = mg
1 lbf = 1 lbm How can this be?
Because this really should be written as:
N = (kg) x (9.81 m/s2)
W = mg/gc
In this case, 1 kg of mass  1 N of force
The gravitational constant, gc is numerically
equivalent to the value of gravity on earth and
converts lbmass to lbforce.
1 lbf = (1 lbm) x ( 32.2 ft/sec2)
= 1 lbm
2
{gc = 32.2 (lbm/lbf)(ft/sec )}
Note: g and gc can also be 386 in/sec2