# Imperial units

system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced
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The Imperial units or the Imperial system is a collection of measurement units. An Act of Parliament in 1824 created it from traditional English units. Commonwealth countries used this system from 1824 until they changed to the metric system. The imperial system is very similar to the American system but there are some differences.

## Length

inch link foot yard pole chain furlong mile league metre
1 inch 1 25198 112 136 1198 1792 17,920 163,360 1190,080 0.0254
1 link 7+​2325 1 3350 1150 125 1100 11,000 18,000 124,000 0.201168
1 foot 12 1+​1733 1 13 233 166 1660 15,280 115,840 0.3048
1 yard 36 4+​611 3 1 211 122 1220 11,760 15,280 0.9144
1 pole 198 25 16+​12 5+​12 1 14 140 1320 1960 5.0292
1 chain 792 100 66 22 4 1 110 180 1240 20.1168
1 furlong 7,920 1,000 660 220 40 10 1 18 124 201.168
1 mile 63,360 8,000 5,280 1,760 320 80 8 1 13 1,609.344
1 league 190,080 24,000 15,840 5,280 960 240 24 3 1 4,828.032

The British nautical mile used to be 6080 feet. In 1970 the UK adopted the international definition of 1852 metres.

## Measures of area

Derived Square rods (sq poles) Square miles Square feet Hectares (Metric) Square Metres (Metric)
1 square foot = 1 foot x 1 foot = 0.003673095
square rods
= 0.00000003587
square mile
= 1 square foot = 0.000009289257 ha = 0.09290304 m²
1 perch = 1 rod × 1 rod = 1 square rods = ​1102400 square mile = 272.25 square feet = 0.002529 ha = 25.29285264 m²
1 rood = 1 furlong × 1 rod = 40 square rods = ​12560 square mile = 10890 square feet = 0.10117141056 ha = 1011.7141056 m²
1 acre = 1 furlong × 1 chain = 160 square rods = ​1640 square mile = 43560 square feet = 0.40468564224 ha = 4046.8564224 m²

## Volume

Liquid
ounce gill pint quart gallon litre
1 (fluid) ounce 1 15 120 140 1160 0.028 413
1 gill 5 1 14 18 132 0.142 065
1 pint 20 4 1 12 18 0.568 261
1 quart 40 8 2 1 14 1.136 522
1 gallon 160 32 8 4 1 4.546 09
1 peck 1 kenning or bucket 1 bushel 1 strike = 2 gal = 9.092 18 L = 2 pecks = 4 gal = 18.184 36 L = 2 kennings = 4 pecks = 8 gal = 36.368 72 L = 2 bushels = 16 gal = 72.737 44 L = 8 bushels = 64 gal = 290.949 76 L = 4 quarters = 32 bushels = 256 gal = 1163.799 04 L = 10 quarters = 80 bushels = 640 gal = 2909.497 6 L
1 firkin 1 kilderkin 1 barrel 1 hogshead = 9 gal = 40.914 81 L = 2 firkin = 18 gal = 81.829 62 L = 2 kilderkin = 4 firkin = 36 gal = 163.659 24 L = 3 kilderkin = 6 firkin = 54 gal = 245.488 86 L

The full table of British apothecaries’ measure is:

1 minim 1 (fluid) scruple 1 (fluid) dram or fluidram = 0.059 193 880 208¯3 mL = 20 minims = 1.183 877 604 1¯6 mL = 3 scruples = 60 minims = 3.551 632 812 5 mL = 8 drachms = 480 minims = 28.413 062 5 mL = 20 ounces = 568.261 25 mL = 8 pints = 160 ounces = 4.546 09 L

For a comparison to the United States customary units see the article on Comparison of the Imperial and US customary systems.

## Mass and weight

1 grain 1 drachm 1 ounce = 64.798 91 mg = 1/16 ounce = 1/256 pound = 1.771 845 195 312 5 g = 1/16 pound = 28.349 523 125 g = 7000 grains = 453.592 37 g = 14 pounds = 6.350 293 18 kg = 2 stone = 28 pounds = 12.700 586 36 kg = 4 quarters = 112 pounds = 50.802 345 44 kg = 20 hundredweight = 2240 pounds = 1016.046 908 8 kg