# USEFUL UNIT CONVERSIONS

This page may be updated as we encounter new units.  Common unit conversions (such as 1 yard = 3 feet, or 1 day = 24 hours) will not appear here.

# Distance

1 m = 3.281 ft

1 mi = 1609 m

1 mi = 5280 ft

1 m = 100 cm

1 m = 1000 mm

1 km = 1000 m

Force

1 lb = 4.448 N

1 lb = 7000 grains

Power

1 Hp = 550 ft-lb/s

1 Hp = 746 W

1 W = 1 J/s

Speed

1 m/s = 2.237 mph

Weight and mass

1 kg weighs 9.8 N

1 kg weighs 2.203 lb

1 kg = 1000 g

(a kilogram is the mass of 1 liter of water)

1 u = 1.6605 x 10-27 kg

1 gram = 15.432358 grains

Volume

1000 ml = 1 l

1 ml = 1 cm3

1 ft3 = 7.481 gal

1 gal = 3.786 l

1 l = 10 cm x 10 cm x 10 cm

(a liter is the volume of a cube that has sides of length 0.10 meters)

Energy

1 J = 1 Nm = 0.738 ft.lb

1 cal = 4.186 J

1 Cal = 1000 cal = 1 kcal

1 BTU = 252 cal

Pressure

1 Pa = 1 N/m2 = 1.45 x 10-4 psi

1 kPa = 1000 Pa

1 atm = 14.7 psi = 101.3 kPa

760 mm Hg = 1 atm

Blood pressure is measured in units of mm Hg (millimeters of Mercury – the pressure required to raise Mercury so many mm in a tube).  So if a person’s systolic pressure is “140” that is 140 mm Hg).

Temperature

100 K = 180 R

Celsius = K – 273

Celsius & Fahrenheit are not true temperature units.

Fahrenheit = R - 460

1 Bq = 1 decay/sec
1 Ci = 37 x 109 Bq

Time

1 year = 3.156 x 107 sec

1 year = 31,560,000 sec

Charge

1 C = 6.24151 x 1018 e

Angle

1 Revolution = 360o

2p “radians” is just 2p because radians are a dimensionless ratio, not a regular unit.

1 Revolution = 2p