Thermal Metric and Other Conversion Factors (Energy Engineering)

The following tables appeared in the January 2007 issue of the Energy Information Administration’s Monthly Energy Review. The Energy Information Administration is a statistical agency of the U.S. Department of Energy.

Table 1 Metric Conversion Factors

These metric conversion factors can be used to calculate the metric-unit equivalents of values expressed in U.S. Customary units. For example, 500 short tons are the equivalent of 453.6 metric tons (500 short tons X 0.9071847 metric tons/short ton = 453.6 metric tons).

Type of Unit U.S. Unit Equivalent in Metric Units
Mass 1 short ton (2,000 lb) = 0.907 184 7 metric tons (t)
1 long ton = 1.016 047 metric tons (t)
1 pound (lb) = 0.453 592 37a kilograms (kg)
1 pound uranium oxide (lb U3Os) = 0.384 647b kilograms uranium (kgU)
1 ounce, avoirdupois (avdp oz) = 28.349 52 grams (g)
Volume 1 barrel of oil (bbl) = 0.158 987 3 cubic meters (m3)
1 cubic yard (yd3) = 0.764 555 cubic meters (m3)
1 cubic foot (ft3) = 0.028 316 85 cubic meters (m3)
1 U.S. gallon (gal) = 3.785 412 liters (L)
1 ounce, fluid (fl oz) = 29.573 53 milliliters (mL)
1 cubic inch (in3) = 16.387 06 milliliters (mL)
Length 1 mile (mi) = 1.609 344a kilometers (km)
1 yard (yd) 0.914 4a meters (m)
1 foot (ft) = 0.304 8a meters (m)
1 inch (in) = 2.54a centimeters (cm)
Area 1 acre = 0.404 69 hectares (ha)
1 square mile (mi2) = 2.589 988 square kilometers (km2)
1 square yard (yd2) = 0.836 127 4 square meters (m2)
1 square foot (ft2) = 0.092 903 04a square meters (m2)
1 square inch (in2) = 6.451 6a square centimeters (cm2)
Energy 1 British thermal unit (Btu)c = 1,055.055 852 62a joules (J)
1 calorie (cal) = 4.186 8a joules (J)
1 kilowatthour (kWh) = 3.6a megajoules (MJ)
Temperatured 32 degrees Fahrenheit (°F) = 0a degrees Celsius (°C)
212 degrees Fahrenheit (°F) = 100a degrees Celsius (°C)

aExact conversion.


Calculated by the Energy Information Administration.

cThe Btu used in this table is the International Table Btu adopted by the Fifth International Conference on Properties of Steam, London, 1956.

dTo convert degrees Fahrenheit (°F) to degrees Celsius (°C) exactly, subtract 32, then multiply by 5/9.

Notes: • Spaces have been inserted after every third digit to the right of the decimal for ease of reading. • Most metric units belong to the International System of Units (SI), and the liter, hectare, and metric ton are accepted for use with the SI units.

Table 2 Metric Prefixes

The names of multiples and subdivisions of any unit may be derived by combining the name of the unit with prefixes as below.

Unit Multiple Prefix Symbol Unit Subdivision Prefix Symbol
101 deka da 10-1 deci D
102 hecto h 10 ” 2 centi c
103 kilo k 10 -3 milli m
106 mega M 10 – 6 micro n
109 giga G 10 -9 nano n
1012 tera T 10 -12 pico p
1015 peta P 10 -15 femto f
1018 exa E 10 -18 atto a
1021 zetta Z 10 -21 zepto z
1024 yotta Y 10 -24 yocto y

Table 3 Other Physical Conversion Factors

The factors below can be used to calculate equivalents in various physical units commonly used in energy analyses. For example, 10 barrels are the equivalent of 420 U.S. gallons (10 barrels x 42 gallons/barrel = 420 gallons).

Energy Source Original Unit Equivalent in Final Units
Petroleum 1 barrel (bbl) = 42a U.S. gallons (gal)
Coal 1 short ton = 2,000a pounds (lb)
1 long ton = 2,240a pounds (lb)
1 metric ton (t) = 1,000a kilograms (kg)
Wood 1 cord (cd) = 1.25b shorts tons
1 cord (cd) = 128a cubic feet (ft3)

aExact conversion.


Calculated by the Energy Information Administration.

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