yards per hour etc. Return to the top of this
document
The SI unit of length is the meter. To change any of these other units of length
into their equivalent values in meters use the operation and conversion factor
given. Those marked with # are exact. Other values are given to an appropriate
degree of accuracy. Where some uncertainty is indicated it means that a good idea of
the size of the unit can be given but that a better value would depend upon knowing the
period and/or culture in which the unit was being used.
angstroms divide by 10 000 000 000 #
astronomical units x 149 598 550 000
barleycorns x 0.008 467
centimeters x 0.01 #
chains (surveyors') x 20.1168 #
cubits x (0.45 to 0.5)
ells (UK) x 0.875 (but many variations)
ems (pica) x 0.004 233 3
fathoms x 1.8288 #
feet (UK and US) x 0.3048 #
feet (US survey) x 0.3048 006 096
furlongs x 201.168 #
hands x 0.106 #
inches x 0.0254 #
kilometers x 1000 #
leagues x (4000 to 5000)
light years x 9 460 500 000 000 000
links (surveyors') x 0.201 168 #
meters [m] 1
microns (=micrometers) x 0.000 001 #
miles (UK and US) x 1609.344 #
miles (nautical) x 1852 #
parsecs x 30 856 770 000 000 000
perch (=rods or poles) x 5.0292 #
picas x 0.004 233 333
points (printers') x 0.000 352 777
yards x 0.9144 #
Area
The S I unit of area is the square meter. To change any of these other units of
area into their equivalent values in square meters use the operation and conversion
factor given. Those marked with # are exact. Other values are given to an
appropriate degree of accuracy. Where some uncertainty is indicated it means that a
good idea of the size of the unit can be given but that a better value would depend upon
knowing the period and/or culture in which the unit was being used.
acres x 4046.856 422 4 #
ares x 100 #
circular inches x 0.000 506 707 479
hectares x 10 000 #
hides x 485 000 (with wide variations)
roods x 1011.714 105 6 #
square centimeters x 0.000 1 #
square feet (UK and US) x 0.092 903 04 #
square feet (US survey) x 0.092 903 411 613
square inches x 0.000 645 16 #
square kilometers x 1 000 000 #
square meters 1
square miles x 2 589 988.110 336 #
square millimeters x 0.000 001 #
squares (of timber) x 9.290 304 #
square rods (or poles) x 25.292 852 64 #
square yards x 0.836 127 36 #
townships x 93 239 571.972
The SI unit of volume is the cubic meter. However, this seems to be much less used than
the liter (1000 liters = 1 cubic meter).To change any of these other units of
volume into their equivalent values in liters use the operation and conversion
factor given. Those marked with # are exact. Other values are given to an
appropriate degree of accuracy.
barrels (oil) x 158.987 294 928 #
bushels (UK) x 36.368 72 #
bushels, dry (US) x 35.239 070 166 88 #
centiliters x 0.01 #
cubic centimeters x 0.001 #
cubic decimeters 1
cubic dekameters x 1 000 000 #
cubic feet x 28.316 846 592 #
cubic inches x 0.016 387 064 #
cubic meters x 1000 #
cubic millimeters x 0.000 001 #
cubic yards x 764.554 857 984 #
deciliters x 0.1 #
fluid ounces (UK) x 0.028 413 062 5 #
fluid ounces (US) x 0.029 573 534 562 5 #
gallons (UK) x 4.546 09 #
gallons, dry (US) x 4.404 883 770 86 #
gallons, liquid (US) x 3.785 411 784 #
liters [l or L] 1
milliliters x 0.001 #
pints (UK) x 0.568 261 25 #
pints, dry (US) x 0.550 610 471 357 5 #
pints, liquid (US) x 0.473 176 473 #
quarts (UK) x 1.136 522 5 #
quarts, dry (US) x 1.101 220 942 715 #
quarts, liquid (US) x 0.946 352 946 #
Mass (or Weight)
The SI unit of mass is the kilogram. To change any of these other units of mass
into their equivalent values in kilograms use the operation and conversion factor
given. Those marked with # are exact. Other values are given to an appropriate
degree of accuracy.
carats, metric x 0.000 2 #
grains x 0.000 064 798 91 #
grams x 0.001 #
hundredweights, long x 50.802 345 44 #
hundredweights, short x 45.359 237 #
kilograms [kg] 1
kips x 453.592 37 #
newtons divide by 9.806 65 #
ounces, avoirdupois x 0.028 349 523 125 #
ounces, troy x 0.031 103 476 8 #
pounds x 0.453 592 37 #
slugs (or g-pounds) x 0.068 521
stones x 6.350 293 18 #
tons (UK or long) x 1016.046 908 8 #
tons (US or short) x 907.184 74 #
tonnes x 1000 #
Line density
Line density is a measure of mass per unit length. The S I compatible unit of line
density is kilograms/meter. A major use of line density is in the textile industry
to indicate the coarseness of a yarn or fiber. For that purpose the SI unit is rather
large so the preferred unit there is the tex. (1 tex = 1 gram/kilometer) To change
any of these other units of line density into their equivalent values in kilograms/meter
use the operation and conversion factor given. Those marked with # are exact. Other
values are given to an appropriate degree of accuracy.
denier divide by 9 000 000 #
drex divide by 10 000 000 #
grams/centimeter divide by 10 #
grams/kilometer (tex) divide by 1 000 000 #
grams/meter divide by 1000 #
grams/millimeter 1
kilograms/kilometer divide by 1000 #
kilograms/meter 1
milligrams/centimeter divide by 10 000 #
milligrams/millimeter divide by 1000 #
ounces/inch x 1.116 125
ounces/foot x 0.093 01
pounds/inch x 17.858
pounds/foot x 1.488 164
pounds/yard x 0.496 055
pounds/mile x 0.000 281 849
tex divide by 1 000 000 #
tons(UK)/mile x 0.631 342
tons(US)/mile x 0.563 698
tonnes/kilometer 1
Density
Density is the shortened term generally used in place of the more accurate description volumetric
density.It is a measure of mass per unit volume. The S I compatible unit of density is
kilograms/cubic meter. However, this a rather large unit for most purposes (iron is
over 7000, wood is about 600 and even cork is over 200). A much more useful size of unit
is kilograms/liter (for which the previous values then become 7, 0.6 and 0.2
respectively). This unit also has the great advantage of being numerically unchanged for
grams/cubic centimeter and tonnes/cubic meter. To change any of these other units of
density into their equivalent values in kilograms/liter use the operation and
conversion factor given. Those marked with # are exact. Other values are given to
an appropriate degree of accuracy.
grains/gallon(UK) divide by 70 156
grains/gallon(US) divide by 58 418
grams/cubic centimeter 1
grams/liter divide by 1000 #
grams/milliliter 1
kilograms/cubic meter divide by 1000 #
milligrams/milliliter divide by 1000 #
milligrams/liter divide by 1 000 000 #
kilograms/liter 1
ounces/cubic inch x 1.729 994 044
ounces/gallon(UK) x 0.006 236 023
ounces/gallon(US) x
pounds/cubic inch x 27.679 904
pounds/cubic foot x 0.016 018 463
pounds/gallon(UK) x 0.099 776 373
pounds/gallon(US) x 0.119 826 427
tonnes/cubic meter 1
tons(UK)/cubic yard x 1.328 939 184
tons(US)/cubic yard x 1.186 552 843
Energy or work
The S I unit of energy or work is the joule. To change any of these other units
of energy or work into their equivalent values in joules use the operation and
conversion factor given. Those marked with # are exact. Other values are given to
an appropriate degree of accuracy.
British thermal units divide by 1055.75 #
calories divide by 4.1868 #
centigrade heat units x 1900.4
ergs divide by 10 000 000 #
foot pounds-force x 1.355 817
foot poundals x 0.042 140
gigajoules [GJ] x 1000 000 000 #
horsepower hours x 2 684 520
joules [J] 1
kilocalories divide by 4186.8 #
kilogram-force meters x 9.806 65 #
kilojoules [kJ] x 1000 #
kilowatt hours [kWh] x 3 600 000 #
megajoules [MJ] x 1 000 000 #
newton meters [Nm] x 1 #
therms x 105 575 000 #
watt seconds [Ws] 1
watt hours [Wh] x 3600 #
Force
The S I unit of force is the newton. To change any of these other units of force
into their equivalent values in newtons use the operation and conversion factor
given. Those marked with # are exact. Other values are given to an appropriate
degree of accuracy.
dynes divide by 100 000 #
kilograms force x 9.806 65 #
kilonewtons [kN] x 1000 #
kips x 4448.222
meganewtons [MN] x 1 000 000 #
newtons [N] 1
pounds force x 4.448 222
poundals x 0.138 255
sthenes (=kN) x 1000
tonnes force x 9806.65 #
tons(UK) force x 9964.016
tons(US) force x 8896.443
Fuel Consumption
Fuel consumption of any means of transport (car, airplane, ship etc.) that uses fuel is
a measure giving the relationship between the distance traveled for an amount of fuel
used. The most common example is the car where it is usually expressed (in
English-speaking countries) in miles per gallon.
It could also be expressed in gallons per mile. However, for a car the latter method gives
a rather small figure: 35 miles per gallon is about 0.0286 gallons per mile. In that case
it would be better to give a figure for 100 miles, so it would be 2.86 gallons per 100
miles. That is the metric way of expressing fuel consumption - as liters per 100
kilometers.
The rules below give a way of converting some of these different forms of measurement of
fuel consumption. All the values are given to an accuracy of 4 significant figures.
To change into
miles per gallon (UK) miles per gallon (US) multiply by 0.833
miles per gallon (UK) miles per liter multiply by 0.22
miles per liter miles per gallon (UK) multiply by 4.456
miles per gallon (UK) kilometers per liter multiply by 0.354
miles per gallon (US) miles per gallon (UK) multiply by 1.2
miles per gallon (US) miles per liter multiply by 0.2642
miles per liter miles per gallon (US) multiply by 3.785
miles per gallon (US) kilometers per liter multiply by 0.4251
X miles per gallon gallons per 100 miles, divide 100 by X
(both gallons must of the same type)
X miles per gallon (UK) liters per 100 miles, divide 282.5 by X
X miles per gallon (US) liters per 100 miles, divide 235.2 by X
Power
The S I unit of power is the watt. To change any of these other
units of energy or work into their equivalent values in watts use the operation and
conversion factor given. Those marked with # are exact. Other values are given to
an appropriate degree of accuracy.
Btu/hour x 0.293 071
Btu/minute x 17.584 263
Btu/second x 1055.055
calories/hour x 0.001 639
calories/minute x 0.069 78
calories/second x 4.1868
ft lb-force/minute x 0.022 597
ft lb-force/second x 1.355 82
gigawatts [GW] x 1 000 000 000
horsepower x 745.7
watts [W] 1
joules/hour divide by 3600 #
joules/minute divide by 60 #
joules/second 1
kilocalories/hour x 1.163
kilocalories/minute x 69.78
kg-force meters/hour x 0.002 724
kg-force meters/minute x 0.163 444
kilowatts [kW] x 1000 #
megawatts [MW] x 1 000 000 #
Pressure or Stress
The S I unit of pressure is the pascal. The units of pressure
are defined in the same way as those for stress - force/unit area. To change any of these
other units of pressure (or stress) into their equivalent values in pascals use the
operation and conversion factor given. Those marked with # are exact. Other values
are given to an appropriate degree of accuracy.
atmospheres x 101 325
bars x 100 000 #
centimeters of mercury x 1333.22
centimeters of water x 98.066 5 #
feet of water x 2989.066 92 #
inches of water x 249.088 91 #
inches of mercury x 3386.388
kg-force/sq.centimeter x 98 066 5 #
kg-force/sq.meter x 9.806 65 #
kilonewton/sq.meter x 1000 #
kilopascal [kPa] x 1000 #
kips/sq.inch x 6 894 760
meganewtons/sq.meter x 1 000 000 #
meters of water x 9806.65 #
millibars x 100 #
pascals [Pa] 1
millimeters of mercury x 133.322
millimeters of water x 9.806 65 #
newtons/sq.centimeter x 10 000
newtons/sq.meter 1
newtons/sq.millimeter x 1 000 000 #
pounds-force/sq.foot x 47.880
pounds-force/sq.inch x 6894.757
poundals/sq.foot x 1.448 16
tons(UK)-force/sq.foot x 107 251
tons(UK)-force/sq.inch x 15 444 256
tons(US)-force/sq.foot x 95 760
tons(US)-force/sq.inch x 13 789 500
tonnes-force/sq.cm x 98 066 500 #
tonnes-force/sq.meter x 9806.65 #
Speed
The S I compatible unit of speed is meters/second. To change any of these other
units of speed into their equivalent values in meters/second use the operation and
conversion factor given. Those marked with # are exact. Other values are given to
an appropriate degree of accuracy.
centimeters/minute divide by 6000 #
centimeters/second divide by 100 #
feet/hour divide by 11 811
feet/minute x 0.005 08 #
feet/second x 0.3048 #
inches/minute divide by 2362.2
inches/second x 0.0254 #
kilometers/hour divide by 0.06 #
kilometers/second x 1000 #
knots x 0.514 444
Mach number x 331.5
meters/hour divide by 3600 #
meters/minute divide by 60 #
meters/second [m/s] 1
miles/hour x 0.447 04 #
miles/minute x 26.8224 #
miles/second x 1609.344 #
yards/hour divide by 3937
yards/minute x 0.015 24
yards/second x 0.9144 #
Spread Rate (by mass)
The spread rate of a substance is a measure of how much of it there is covering a unit
area. The 'how much' can be measured by volume or by mass. The S I compatible unit of
spread rate by mass is kilograms/square meter. It is also a measure of area density
(mass/unit area) and is similar to - but not the same as - pressure, which is force/unit
area. For the rainfall conversions a density of 1 kg/liter has been assumed. To change any
of these other units of spread rate into their equivalent values in kilograms/square meter
use the operation and conversion factor given. Those marked with # are exact. Other
values are given to an appropriate degree of accuracy.
grams/sq.centimeter x 10 #
grams/sq.meter divide by 1000 #
inches of rainfall x 2.54
kilograms/hectare divide by 10 000 #
kilograms/sq.centimeter x 10 000 #
milligrams/sq.meter divide by 1000 #
millimeters of rainfall 1
kilograms/sq.meter 1
ounces/sq.foot x 0.305 152
ounces/sq.inch x 43.942
ounces/sq.yard divide by 49.494
pounds/acre divide by 8921.791
pounds/sq.foot x 4.882 428
pounds/sq.inch x 703.07
pounds/sq.yard x 0.542 492
tonnes/hectare divide by 10 #
tons(UK)/acre divide by 3.982 942
tons(US)/acre divide by 4.460 896
Spread Rate (by volume)
The spread rate of a substance is a measure of how much of it there is covering a unit
area. The 'how much' can be measured by volume or by mass. The S I compatible unit of
spread rate by volume is cubic meters/square meter. However, this is a rather large
unit for most purposes and so liters/square meter is often preferred. To change any of
these other units of spread rate into their equivalent values in liters/square meter
use the operation and conversion factor given. Those marked with # are exact. Other
values are given to an appropriate degree of accuracy.
cubic feet/acre divide by 142.913
cubic inches/sq.yard divide by 51.024
cubic yards/sq.mile divide by 3387.577
cubic meters/hectare divide by 10 #
cubic meters/sq.km divide by 1000 #
cubic meters/sq.meter x 1000 #
fl. ounces(UK)/sq.yard divide by 29.428
liters/square meter 1
gallons(UK)/acre divide by 890.184
gallons(US)/acre divide by 1069.066
gallons(UK)/hectare divide by 2199.692
gallons(US)/hectare divide by 2641.721
inches of rainfall x 25.4 #
liters/hectare divide by 10 000 #
milliliters/sq.meter divide by 1000 #
millimeters of rainfall 1
Torque
The S I compatible unit of torque is the newton meter. To change any of these
other units of torque into their equivalent values in newton meters use the
operation and conversion factor given. Those marked with # are exact. Other values
are given to an appropriate degree of accuracy.
ergs (= dyne cm) divide by 10 000 000 #
gram-force centimeters x 0.000 098 066 5 #
kg-force centimeters x 0.098 066 5 #
kg-force meters x 9.806 5 #
newton centimeters divide by 100 #
newton meters [Nm] 1
ounce-force inches divide by 141.612
pound-force inches x 0.112 984
pound-force feet x 1.355 818
poundal feet x 0.042 140
ton(UK)-force feet x 3 037.032
ton(US)-force feet x 2 711.636
tonne-force meters x 9 806.65 #
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