General Tables of Units of Measurement

These tables have been prepared for the benefit of those requiring tables of units for occasional ready reference. In Section 4 of this Appendix, the tables are carried out to a large number of decimal places and exact values are indicated by underlining. In most of the other tables, only a limited number of decimal places are given, therefore making the tables better adopted to the average user.

The data presented here is derived from publications of NIST, so it is in the public domain. However, this HTML implementation is not in the public domain. It is provided to make for easier access.

1. Tables of Metric Units of Measurement

In the metric system of measurement, designations of multiples and subdivisions of any unit may be arrived at by combining with the name of the unit the prefixes deka, hecto, and kilo meaning, respectively, 10, 100, and 1 000, and deci, centi, and milli, meaning, respectively, one-tenth, one-hundredth, and one- thousandth. In some of the following metric tables, some such multiples and subdivisions have not been included for the reason that these have little, if any currency in actual usage.

In certain cases, particularly in scientific usage, it becomes convenient to provide for multiples larger than 1 000 and for subdivisions smaller than one-thousandth. Accordingly, the following prefixes have been introduced and these are now generally recognized:

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

Thus a kilometer is 1000 meters and a millimeter is 0.001 meter.

Units of Length

10 millimeters (mm)		= 1 centimeter (cm)
10 centimeters		= 1 decimeter (dm) = 100 millimeters
10 decimeters		= 1 meter (m) = 1000 millimeters
10 meters		= 1 dekameter (dam)
10 dekameters		= 1 hectometer (hm) = 100 meters
10 hectometers		= 1 kilometer (km) = 1000 meters

Units of Area

100 square millimeters (mm²)		= 1 square centimeter (cm²)
100 square centimeters		= 1 square decimeter (dm²)
100 square decimeters		= 1 square meter (m²)
100 square meters		= 1 square dekameter (dam²) = 1 are
100 square dekameters		= 1 square hectometer (hm²) = 1 hectare (ha)
100 square hectometers		= 1 square kilometer (km²)

Units of Liquid Volume

10 milliliters (mL)		= 1 centiliter (cL)
10 centiliters		= 1 deciliter (dL) = 100 milliliters
10 deciliters		= 1 liter^† = 1000 milliliters
10 liters		= 1 dekaliter (daL)
10 dekaliters		= 1 hectoliter (hL) = 100 liters
10 hectoliters		= 1 kiloliter (kL) = 1000 liters

Units of Volume

1000 cubic millimeters (mm3)		= 1 cubic centimeter (cm³)
1000 cubic centimeters		= 1 cubic decimeter (dm3) = 1 000 000 cubic millimeters
		= 1 cubic decimeter (dm3) = 1 000 000 cubic millimeters
1000 cubic decimeters		= 1 cubic meter (m³) = 1 000 000 cubic centimeters = 1 000 000 000 cubic millimeters

Units of Mass

10 milligrams (mg)		= 1 centigram (cg)
10 centigrams		= 1 decigram (dg) = 100 milligrams
10 decigrams		= 1 gram (g) = 1000 milligrams
10 grams		= 1 dekagram (dag)
10 dekagrams		= 1 hectogram (hg) = 100 grams
10 hectograms		= 1 kilogram (kg) = 1000 grams
1000 kilograms		= 1 megagram (Mg) or 1 metric ton(t)

† By action of the 12th General Conference on Weights and Measures (1964) the liter is a special name for the cubic decimeter.

2. Tables of U.S. Units of Measurement^††

In these tables where foot or mile is underlined, it is survey foot or U.S. statute mile rather than international foot or mile that is meant.

Units of Length

12 inches (in)		= 1 foot (ft)
3 feet		= 1 yard (yd)
16-1/2 feet		= 1 rod (rd), pole, or perch
40 rods		= 1 furlong (fur) = 660 feet
8 furlongs		= 1 U.S. statute mile (mi) = 5280 feet
1852 meters		= 6076.115 49 feet (approximately) = 1 international nautical mile

Units of Area^†††

144 square inches (in2)		= 1 square foot (ft²)
9 square feet		= 1 square yard (yd²) = 1296 square inches
272-1/4 square feet		= 1 square rod (sq rd)
160 square rods		= 1 acre = 43 560 square feet
640 acres		= 1 square mile (mi²)
1 mile square		= 1 section of land
6 miles square		= 1 township = 36 sections = 36 square miles

Units of Volume^†††

1728 cubic inches (in3)		= 1 cubic foot (ft3)
27 cubic feet		= 1 cubic yard (yd3)

Gunter’s or Surveyors Chain Units of Measurement

0.66 foot (ft)		= 1 link (li)
100 links		= 1 chain (ch) = 4 rods = 66 feet
80 chains		= 1 U.S. statute mile (mi) = 320 rods = 5280 feet

†† This section lists units of measurement that have traditionally been used in the United States. In keeping with the Omnibus Trade and Competitiveness Act of 1988, the ultimate objective is to make the International System of Units the primary measurement system used in the United States.

††† Squares and cubes of customary but not of metric units are sometimes expressed by the use of abbreviations rather than
symbols. For example, sq ft means square foot, and cu ft means cubic foot.

3. Notes on British Units of Measurements

In Great Britain, the yard, the avoirdupois pound, the troy pound, and the apothecaries pound are identical with the units of the same names used in the United States. The tables of British linear measure, troy mass, and apothecaries mass are the same as the corresponding United States tables, except for the British spelling "drachm" in the table of apothecaries mass. The table of British avoirdupois mass is the same as the United States table up to 1 pound; above that point the table reads:

14 pounds		= 1 stone
2 stones		= 1 quarter = 28 pounds
4 quarters		= 1 hundredweight = 112 pounds
20 hundredweight		= 1 ton = 2240 pounds

The present British gallon and bushel--known as the "Imperial gallon" and "Imperial bushel"--are, respectively, about 20 percent and 3 percent larger than the United States gallon and bushel. The Imperial gallon is defined as the volume of 10 avoirdupois pounds of water under specified conditions, and the Imperial bushel is defined as 8 Imperial gallons. Also, the subdivision of the Imperial gallon as presented in the table of British apothecaries fluid measure differs in two important respects from the corresponding United States subdivision, in that the Imperial gallon is divided into 160 fluid ounces (whereas the United States gallon is divided into 128 fluid ounces), and a "fluid scruple" is included. The full table of British measures of capacity (which are used alike for liquid and for dry commodities) is as follows:

4 gills		= 1 pint
2 pints		= 1 quart
4 quarts		= 1 gallon
2 gallons		= 1 peck
8 gallons (4 pecks)		= 1 bushel
8 bushels		= 1 quarter

The full table of British apothecaries measure is as follows:

20 minims		= 1 fluid scruple
3 fluid scruples		= 1 fluid drachm = 60 minims
8 fluid drachms		= 1 fluid ounce
20 fluid ounces		= 1 pint
8 pints		= 1 gallon (160 fluid ounces)

4. Tables of Units of Measurement
(all underlined figures are exact)

Units of Length - International Measure^‡

Units	Inches	Feet	Yards	Miles	Centimeters	Meters
1 inch =	1	0.083 333 33	0.027 777 78	0.000 015 782 83	2.54	0.025 4
1 foot =	12	1	0.333 333 3	0.000 189 393 9	30.48	0.304 8
1 yard =	36	3	1	0.000 568 181 8	91.44	0.914 4
1 mile =	63 360	5 280	1 760	1	160 934.4	1609.344
1 centimeter =	0.393 700 8	0.032 808 40	0.010 936 13	0.000 006 213 712	1	0.01
1 meter =	39.370 08	3.280 840	1.093 613	0.000 621 371 2	100	1

Units of Length - Survey Measure^‡

Units	Links	Feet	Rods	Chains	Miles	Meters
1 link =	1	0.66	0.04	0.01	0.000 125	0.201 168 4
1 foot =	1.515 152	1	0.060 606 06	0.015 151 52	0.000 189 393 9	0.304 800 6
1 rod =	25	16.5	1	0.25	0.003 125	5.029 210
1 chain =	100	66	4	1	0.0125	20.116 84
1 mile =	8 000	5 280	320	80	1	1609.347
1 meter =	4.970 960	3.280 833	0.198 838 4	0.049 709 60	0.000 621 369 9	1

‡ One international foot = 0.999 998 survey foot (exactly)
   One international mile = 0.999 998 survey mile (exactly)

Note: 1 survey foot = 1200/3937 meter (exactly)
         1 international foot = 12 x 0.0254 meter (exactly)
         1 international foot = 0.0254 x 39.37 survey foot (exactly)

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