# Conversion Factors - Imperial Units To Metric Units

Conversion Factors
Conversion Factors (Approximate)
Quantity
Imperial Unit
Metric Unit
Imperial to
Metric to
Metric Units
Imperial Units
Length
inch (in)
millimetre (mm) or
1 in = 25.4 mm
1 cm = 0.394 in
centimetre (cm)
foot (ft)
centimetre or metre (m)
1 ft = 30.5 cm
1 m = 3.28 ft
yard (yd)
metre (m)
1 yd = 0.194 m
1 m = 1.09 yd
furlong (fur)
metre (m) or
1 fur = 201 m
1km = 4.97 fur
kilometre (km)
1km = 0.621 mile
mile
kilometre (km)
1 mile = 1.61 km
1m = 3.28 ft
international nautical mile
1 n mile = 1852 m
Mass
ounce (oz)
gram (g)
1 oz = 28.3 g
1 g = 0.0353 oz
pound (lb)
gram (g) or kilogram (kg)
1 lb = 454 g
1 kg = 2.20 lb
stone
kilogram (kg)
1 stone = 6.35 kg
1 kg = 0.157 stone
ton
tonne (t)
1 ton = 1.02 t
1 t = 0.984 ton
Area
square inch (in
2
)
square centimetre (cm
2
)
1 in
2
= 6.45 cm
2
1 cm
2
= 0.155 in
2
2
2
2
2
square foot (ft
)
square centimetre (cm
) or
1 ft
= 929 cm
square metre (m
2
)
1 m
2
= 10.8 ft
2
square yard (yd
2
)
square metre (m
2
)
1 yd
2
= 0.836 m
2
1 m
2
= 1.20 yd
2
2
2
2
perch (p)
square metre (m
)
1 p = 25.3 m
1 m
= 0.0395 p
rood (rd)
hectare (ha)
1 rd = 0.101 ha
1 ha = 9.88 rd
acre (ac)
hectare (ha)
1 ac = 0.405 ha
1 ha = 2.47 ac
square mile
square kilometre (km
2
)
1 square mile = 2.59 km
2
1 km
2
= 0.386 sq. mile
3
3
3
3
3
3
Volume
cubic inch (in
)
cubic centimetre (cm
)
1 in
= 16.4 cm
1 cm
= 0.0610 in
cubic foot (ft
3
)
cubic metre (m
3
)
1 ft
3
= 0.0283 m
3
1 m
3
= 35.3 ft
3
3
3
3
3
3
3
cubic yard (yd
)
cubic metre (m
)
1 yd
= 0.765 m
1 m
= 1.31 yd
bushel (bus)
cubic metre (m
3
)
1 bus = 0040.0364 m
3
1 m
3
= 27.5 bus
Volume (fluids)
fluid ounce (fl oz)
millilitre
1 fl oz = 28.4 ml
1 ml = 0.0352 fl oz
pint (pt)
millilitre (ml) or litre (l)
1 pt = 568 ml
1 litre = 1.76 pt
gallon (gal)
litre (l) or cubic metre (m
3
)
1 gal = 4.55 litre
1 m
3
= 220 gal
3
3
acre foot
cubic metre (m
) or
1 acre foot = 1230 m
megalitre (ML)
= 1.23 ML
1 ML = 0.811 acre foot
Force
pound-force (lbf)
newton (N)
1 lbf = 4.45 N
1 N = 0.225 lbf
ton-force (tonf)
kilonewton (kN)
tonf = 9.96 kN
1 kN = 0.100 tonf
Pressure
pound per square inch (psi)
kilopascal (kPa)
1 psi = 6.89 kPa
1 kPa = 0.145 psi
atmosphere (atm)
kilopascal (kPa) or
1 atm = 101 kPa
megapascal (MPa)
1 MPa = 9.87 atm
ton per square inch (ton/in
2
)
megapascal (MPa)
1 ton/in
2
= 15.4 MPa
1 MPa = 0.647 ton/in
2
inch of mercury (in Hg)
milibar (b)
1 in Hg = 33.9 mb
1 mb = 0.0295 in Hg
(for meteorology)
1 mb = 100 Pa
Velocity
mile per hour (mph)
kilometre per hour (km/h)
1 mph = 1.61 km/h
1 km/h = 0.621 mph
knot (kn)
= 1 kn = 1.85 km/h
Temperature
degree Fahrenheit (
o
F)
degree Celsius (
o
C)
o
C = 5/9 (F - 32)
o
F = 9/5 (C + 32)
3
3
3
3
3
3
Density
pound per cubic inch (lb/in
)
gram per cubic centimetre (g/cm
)
1 lb/in
= 27.7 g/cm
1 g/cm
= 0.0361 lb/in
= tonne per cubic metre (t/m
3
)
1 lb/in
3
= 27.7 t/m
3
1 t/m
3
= 0.0361 lb/in
3
3
3
3
3
2
3
ton per cubic yard
tonne per cubic metre (t/m
)
1 ton/yd
= 1.33 t/m
1 t/m
= 0.75
ton/yd
Energy
British thermal unit (btu)
kilojoule (kJ)
1 Btu = 1.06 kJ
1 kJ = 0.948 btu
3
therm
megajoule (MJ)
1 therm = 106 MJ
1 MJ = 9.48 x 10
therm
(for electrical energy)
kilowatt hour (kWh)
= kWh = 3.60 MJ
Power
horsepower (hp)
kilowatt (kW)
1 hp = 0.746 kW
1 kW = 1.34 hp
Time
second (s)
minute (min)
1 min = 60s
hour (h)
1 h = 3600s
Frequency
cycle per second (c/s)
hertz (Hz)
1 c/s = 1 Hz
1 Hz = 1 c/s
Angular Velocity
revolution per minute (rpm)
revolution per minute (rpm)