Weights and Measures

Length
Imperial: Basic Unit 1 inch = 0.0254 m exactly
originally the length of three grains of barley laid end to end
				1 line	(≈2.12 mm)
		4 lines	=	1 barleycorn	(≈8.47 mm)
		3 barleycorns	=	1 inch	(2.54 cm)
		12 inches	=	1 foot	(12 inches) (0.3048 m)
		3 feet	=	1 yard	(36 inches) (0.9144 m)
		3¾ feet	=	1 ell	(45 inches) (1.143 m)
		5½ yards	=	1 perch	(198 inches) (5.0292 m)
		1 perch	=	1 pole	(198 inches) (5.0292 m)
		1 perch	=	1 rod	(198 inches) (5.0292 m)
		1 perch	=	1 rood	(198 inches) (5.0292 m)
		4 perches	=	1 chain	(66 feet or 22 yards) (≈20 m)
		10 chains	=	1 furlong	(660 feet or 220 yards) (≈201 m)
		8 furlongs	=	1 mile	(5280 feet or 1760 yards) (1609.344 m)
		3 miles	=	1 league	(15840 feet or 5280 yards) (≈4829 m)
U.S.: Basic Unit 1 inch = 0.0254 m exactly
				1 inch	(0.0254 m)
		12 inches	=	1 foot	(12 inches) (0.3048 m)
		3 feet	=	1 yard	(36 inches) (0.9144 m)
		1760 yards	=	1 mile	(5280 feet or 1760 yards) (1609.344 m)
Scottish (abandoned): Basic Unit 1 inch ≈0.02554 m
				1 inch	(0.02554 m)
		12 inches	=	1 foot	(≈12.065 imperial inches) (≈0.3065 m)
		37 inches	=	1 ell	(≈0.9449 m)
		6 ells	=	1 fall	(≈6.2 imperial yards) (≈5.669 m)
		40 falls	=	1 furlong	(≈226.8 m)
		8 furlongs	=	1 mile	(≈1.127 imperial mile) (≈1814 m)
Imperial and U.S.: Basic Unit 1 inch = 0.0254 m exactly
Nautical Only
		6 feet	=	1 fathom	(6 feet) (1.8288 m)
		20 fathoms	=	1 cable	(120 feet) (36.576 m)
		1 Nautical Mile (Imperial)	=	6080 feet (until 1970)	(120 feet) (1.853184 km)
		1 Nautical Mile (U.S.)	=	6080.2 feet (until 1953)	(120 feet) (1.853249 km)
		1 Nautical Mile	=	1852 m	(≈6076 feet or ≈1.15 miles)
Surveying Only
		7.92 inches	=	1 link	(≈0.2 m)
		100 links	=	1 chain	(792 inches) (≈20 m)
Others
		1 Light Year	≈	5,878,625,373,000 miles
			≈	9.4607304725808×1015 m
		1 mil	=	0.001 inch
			=	25.4 microns	(2.54×10-5m)
		1 Angstrom (1Å)	≈	0.000000003937 inch	(10-10m)
		1 Micron (1μm)	≈	0.00003937 inch	(10-6m)
		1 Millimetre (1mm)	≈	0.03937 inch	(10-3m)
		1 Centimetre (1cm)	≈	0.3937 inch	(10-2m)
		1 Metre (1m)	≈	39.3700787 inch
			≈	3.28083990 foot
			≈	1.09361330 yard
		1 Kilometre (1km)	≈	0.62137119 mile	(103m)
			≈	1093.61330 yards
			≈	3280.83990 feet
		diameter of an electron	≈	5.63588065×10-15 m
			≈	4,507,000,000,000 per inch
		diameter of a proton	≈	1.5×10-15 m	(35% margin of error)
		diameter of 1H atom	≈	1.058×10-10 m
			≈	240,000,000 per inch
		diameter of 16O atom	≈	1.20×10-10 m
			≈	211,000,000 per inch
		length of air molecule	≈	2.40×10-10 m	(O2 and N2 same)
			≈	106,000,000 per inch
		diameter of large atom	≈	6.6×10-10 m	(typical of atoms beyond Na)
			≈	40,000,000 per inch
Area
Imperial: Basic Unit 1 perch = 198 inches or 16½ feet or 5.0292 m exactly
				1 square perch	(272¼ square feet) (≈25.29 m2)
		40 square perches	=	1 rood	(10,890 square feet) (≈1000 m2)
		4 roods	=	1 acre	(43,560 square feet) (≈4000 m2)
		1 furlong × 1 chain	=	1 acre	(43,560 square feet) (≈4000 m2)
		640 acres	=	1 square mile	(27,878,400 square feet) (≈2,600,000 m2)
Others
		1 square inch	=	6.4516 cm2	0.00064516 m2
		1 square foot	=	929.0304 cm2	0.09290304 m2
		1 square yard	≈	0.836127 m2
		1 square mile	≈	2,589,988 m2
		1 barn	=	10-28 m2
		1 square centimetre	≈	0.155 square inch
		1 square metre	≈	10.7639 square foot
			≈	1.19599 square yard
		1 are (a)	=	100 m2	(≈ 4 square perches or ≈0.1 rood)
		1 hectare (ha)	=	10,000 m2	(≈2½ acres)
		1 square kilometre	≈	0.386102 square mile	(100 ha)
			≈	247 acres
Capacity
Imperial: Basic Unit 1 pint = 0.56826125 l exactly
originially the volume of 20 ounces of distilled water
Smallest Unit 1 minim = about the smallest possible drop of water
Imperial Bushel of 1826 = volume of 80 pounds of distilled water in air at 62°F
Fluid Only
				1 minim	(≈59.2 μl)
		20 minims	=	1 fluid scruple	(20 minims) (≈1.18 ml)
		3 fluid scruples	=	1 fluid drachm	(60 minims) (≈3.55 ml)
		8 fluid drachms	=	1 fluid ounce	(480 minims) (≈28.4 ml)
		5 fluid ounces	=	1 gill	(2400 minims) (≈0.142 l)
Fluid or Dry
		4 gills	=	1 pint	(0.56826125 l)
				1 pint	≈1.20095 U.S. fluid pint
		2 pints	=	1 quart	(≈1.14 l)
		2 quarts	=	1 pottle	(≈2.27 l)
		2 pottles	=	1 gallon	(≈4.55 l)
				1 gallon	≈1.20095 U.S. fluid gallon
Dry Only
		2 gallons	=	1 peck	(2 gallons) (≈9.09 l)
		4 pecks	=	1 bushel	(8 gallons) (≈36.4 l)
		8 bushels	=	1 quarter	(64 gallons) (≈291 l)
		84 gallons	=	1 puncheon	(84 gallons) (≈882 l)
		4 quarters	=	1 chaldron	(256 gallons) (≈1164 l)
		5 quarters	=	1 wey	(320 gallons) (≈1455 l)
		2 weys	=	1 last	(640 gallons) (2909.4976 l)
Fluid Only
		9 gallons	=	1 firkin	(9 gallons) (≈40.9 l)
		2 firkins	=	1 kilderkin	(18 gallons) (≈81.8 l)
		2 kilderkins	=	1 barrel	(36 gallons) (≈164 l)
		6 firkins	=	1 hogshead of ale	(54 gallons) (≈491 l)
		7 firkins	=	1 hogshead of wine	(63 gallons) (≈573 l)
		3 barrels	=	1 pipe	(108 gallons) (≈982 l)
		2 pipes	=	1 tun	(216 gallons) (≈1964 l)
Scottish
Wheat only
		553.5625 cubic inches	=	1 Lippy	(≈1.995399 gallons) (≈9.071264 l)
		4 Lippies	=	1 Peck	(≈7.981597 gallons) (≈36.28506 l)
		4 Pecks	=	1 Firlot	(≈31.926386 gallons) (≈145.1402 l)
Anything else
		807.55 cubic inches	=	1 Lippy	(≈2.910935 gallons) (≈13.23374 l)
		4 Lippies	=	1 Peck	(≈11.64374 gallons) (≈52.93350 l)
		4 Pecks	=	1 Firlot	(≈46.57496 gallons) (≈211.7340 l)
Oil
		1 Barrel	=	42 U.S. fluid gallons	(≈34.972308 imperial gallons) (≈159.99 l)
U.S. Fluid Capacity: Basic Unit 1 pint = 0.473176473 l exactly
				1 U.S. fluid ounce	=0.8593670 U.S. dry ounce
					≈1.040842 Imperial fluid ounce
		1 ounce	≈	29.57 ml
		16 ounces	=	1 pint	(≈0.473 l)
				1 U.S. fluid pint	=0.8593670 U.S. dry pint
					≈0.832674 Imperial pint
		2 pints	=	1 quart	(≈0.946 l)
		4 quarts	=	1 gallon	(≈3.785 l)
				1 U.S. fluid gallon	=0.8593670 U.S. dry gallon
					≈0.832674 Imperial gallon
U.S. Dry Capacity: Basic Unit 1 pint = 0.5506104713575 l exactly
				1 U.S. dry ounce	=1.163646 U.S. fluid ounce
					≈1.211172 Imperial fluid ounce
		1 ounce	≈	34.41 ml
		16 ounces	=	1 pint	(≈0.551 l)
				1 U.S. dry pint	=1.163646 U.S. fluid pint
					≈0.968938 Imperial pint
		2 pints	=	1 quart	(≈1.10 l)
		4 quarts	=	1 gallon	(≈4.40 l)
				1 U.S. dry gallon	=1.163646 U.S. fluid gallon
					≈0.968938 Imperial gallon
		8 gallons	=	1 bushel	(≈35.24 l)
Others
		1 mole of ideal gas	≈	22.413996 l	at 32°F or 0°C
			≈	0.791543 cubic feet
			≈	3.59843 U.K. gallon
		1 cubic inch	=	16.387064 cm3
			≈	0.576744 U.K. fluid ounce
			≈	0.554112 U.S. fluid ounce
		1 cubic foot	≈	6.228835 U.K. gallon
			≈	7.48052 U.S. gallon
			≈	28.31685 litre
			≈	0.02831685 m3
		1 cubic yard	≈	168.179 U.K. gallon
			≈	201.975 U.S. gallon
			≈	764.555 litre
		1 litre (1 l)	≈	1.7597539 U.K. pint
			≈	2.1133764 U.S. pint
			≈	1.8161660 U.S. dry pint
			=	1000 cm3
			=	0.001 m3
		1 cubic centimetre (1 cc)	=	1 millilitre (1 ml)
		1 millilitre (1 ml)	≈	16.9 minims
			≈	0.85 fluid scruple
			≈	0.035 U.K. fluid ounce
		1 cubic metre (1 m3)	=	1 stere
			=	1000 litre
			≈	1.3079506 cubic yard
			≈	35.314667 cubic foot
			≈	219.969 U.K. gallon
			≈	264.172 U.S. gallon
		1 cubic mile	=	5.451776×109 cubic yard
			=	1.471980×1011 cubic feet
			≈	9.168718×1011 U.K. gallon
			≈	1.101097×1012 U.S. gallon
			≈	4.168104×1012 litre
Weight
Basic Unit 1 grain, originally the weight of a grain of wheat
Troy: for drugs, jewels, and precious metals
				1 grain	(0.06479891 g)
		4 grains	=	1 carat	(4 grains) (≈0.259 g)
		5 carats	=	1 scruple	(20 grains) (≈1.30 g)
		6 carats	=	1 pennyweight	(24 grains) (≈1.56 g)
		3 scruples	=	1 drachm	(60 grains) (≈3.89 g)
		8 drachms	=	1 ounce	(480 grains) (≈31.1 g)
		20 pennyweight	=	1 ounce	(480 grains) (31.1034768 g)
				1 troy ounce	=1.0971428 avoirdupois ounce
		12 ounces	=	1 pound	(5760 grains) (0.3732417216 kg)
Imperial Avoirdupois
				1 grain	(0.06479891 g)
		27.34375 grains	=	1 dram	(≈1.772 g)
		16 drams	=	1 ounce	(437½ grains) (≈28.35 g)
				1 avoirdupois ounce	=0.9114583 troy ounce
		16 ounces	=	1 pound	(7000 grains) (0.45359237 kg)
		14 pounds	=	1 stone	(14 pounds) (≈6.35 kg)
		2 stones	=	1 quarter	(28 pounds) (≈12.70 kg)
		4 quarters	=	1 hundredweight	(112 pounds) (≈50.80 kg)
		20 hundredweight	=	1 ton	(2240 pounds) (1.0160469088 T)
				1 Imperial ton	=1.12 U.S. ton
Tower: for money
Basic Unit the Tower Pennyweight, the weight of a silver penny
		22½ grains	=	1 pennyweight	(≈1.458 g)
		20 pennyweights	=	1 ounce	(450 grains) (≈29.16 g)
		12 ounces	=	1 pound	(5400 grains) (≈349.9 g)
U.S. Avoirdupois
				1 grain	(≈0.06479891 g) = 1 imperial grain
		437½ grains	=	1 ounce	(≈28.35 g) = 1 imperial ounce
		16 ounces	=	1 pound	(7000 grains) (0.45359237 kg) = 1 imperial pound
		100 pounds	=	1 hundredweight	(45.359237 kg) (≈0.8929 imperial hundredweight)
		20 hundredweight	=	1 ton	(2000 pounds) (0.90718474 T)
				1 U.S. ton	≈0.8929 Imperial ton
Other
		1 milligram (1mg)	≈	0.015432358 grain
		1 gram (1g)	≈	15.432358 grain
			≈	0.0352740 ounce
		1 Lippy weight	≈	28 ounces
		1 kilogram (1kg)	≈	2.2046226 pound
		1 Tonne (1T or 1Mg)	≈	0.9842065 ton
			≈	1.1023113 U.S. ton
Mass
		Mass of 1 Proton	≈	1.67262171×10-27 kg
		Mass of 1 Electron	≈	9.1093826×10-31 kg
		Mass of 12C atom	≈	1.992647×10-26 kg
Energy
		1 calorie	≈	4.185 Joule
		1 kilocalorie (1kcal)	≈	4185 Joule
		1 British thermal unit (1BTU)	=	1055.056 Joule
			≈	0.2520124 kcal
		1 kilowatt hour (1kWH)	=	3,600,000 Joule
			≈	860215 calorie
		1 joule (1J)	≈	0.238948 calorie
			=	3.6 milliwatt hour
			=	10,000,000 erg
		1 electron volt (1eV)	≈	1.60217653×10-19 joule
			≈	96,485 joule per mole
		melt 1 pint ice	≈	190,000 joule
		boil 1 pint frigid water	≈	238,000 joule
		evaporate 1 pint boiling water	≈	1,285,000 joule
		burning 1 pint of whisky	≈	6,600,000 joule
		burning 1 pound of wood	≈	7,000,000 joule
		burning 1 pound of coal	≈	12,000,000 joule
		burning 1 pound of propane	≈	22,834,000 joule
		burning 1 gallon of gasoline	≈	121,000,000 joule
		burning 1 gallon of petrol	≈	145,000,000 joule
		1 kiloton of TNT (1kT)	≈	4.184×1012 joule
			≈	1.16 gigawatt hour (1.16GWH)
			≈	132.6 kilowatt year
		1 megaton of TNT (1MT)	≈	4.184×1015 joule
		1 kg mass equivalent	≈	8.987551787×1016 joule
			≈	21½ megaton
Power
		1 Watt (1 W)	=	1 joule per second
		1 imperial horsepower (1 hp)	≈	745.699872 Watt
		1 kilowatt (1 kW)	≈	1.341022 hp
			≈	raises 1 pint frigid water to boiling in 4 mins
			≈	evaporates 1 pint boiling water in 21 mins
		heat from 1 candle	≈	40 Watt
		radiation from 1 pound of plutonium	≈	251 Watt
		from sun on earth per m2	≈	1366 Watt
		sun's output	≈	3.86×1026 Watt
Electrical
		Charge on electron	≈	1.60217653×10-19 Coulomb
		1 Faraday	≈	96,485.3383 Coulomb per mole
Velocity
		1 mile per hour (1MPH)	=	0.44704 metre per second
			≈	1.466666 foot per second
			=	1.609344 kilometre per hour
			≈	0.868976 knot
		1 metre per second (1m/s)	≈	2.236936 MPH
		1 foot per second (1fps)	≈	0.681818 m/s
		1 knot (1kt)	=	0.51444444444 m/s
			≈	1.15078 MPH
		1 kilometre per hour (1kph)	=	0.2777777777 m/s
			=	1.609344 MPH
		1 speed of light (1c)	≈	299,792,458 m/s
			≈	670,616,542 MPH
			≈	186,282 miles per second
			≈	983 feet per microsecond
Time
		1 minute	=	60 second
		1 hour	=	3600 second
		1 day	=	86400 second
		1 (non-leap) year	=	31,536,000 second	(365 day)
		1 leap year	=	31,622,400 second	(366 day)
		1 average year	=	31,556,952 second	(365.2425 day)
		1 mean tropical year	≈	365.242190419 day
			≈	31,556,925.25 second
Quantity
		1 mole	≈	6.0221418×1023	(2006 estimate)
			≈	602,214,180,000,000,000,000,000
Money
British, until 15th February 1971
U.S., until about 1781
				1 farthing	(¼d)
		4 farthings	=	1 penny (1d)	(1d)
		4 pence	=	1 groat	(4d)
		12 pence	=	1 shilling (1/-)	(12d)
		5 shillings	=	1 crown	(60d)
		20 shillings	=	1 pound (£1)	(240d)
		21 shillings	=	1 guinea	(252d)