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Dictionary of Units / Measurements

# US System of Measurements

Most of the US system of measurements is the same as that for the UK. The biggest differences to be noted are in Capacity which has both liquid and dry measures as well as being based on a different standard - the US liquid gallon is smaller than the UK gallon. There is also a measurement known at the US survey foot. It is gradually being phased out as the maps and land plans are re-drawn under metrication. (The changeover is being made by putting 39.37 US survey feet = 12 metres)

## Length

12 inches = 1 foot

3 feet = 1 yard

220 yards = 1 furlong

8 furlongs = 1 mile

5280 feet = 1 mile

1760 yards = 1 mile

## Capacity (Dry)

2 pints = 1 quart

8 quarts = 1 peck

4 pecks = 1 bushel

## Capacity (Liquid)

16 fluid ounces = 1 pint

4 gills  = 1 pint

2 pints = 1 quart

4 quarts = 1 gallon (8 pints)

## Mass

437.5 grains = 1 ounce

16 ounces = 1 pound (7000 grains)

14 pounds = 1 stone

100 pounds = 1 hundredweight [cwt]

20 cwt = 1 ton (2000 pounds)

## Area

144 sq. inches = 1 square foot

9 sq. feet = 1 square yard

4840 sq. yards = 1 acre

640 acres = 1 square mile

1 sq.mile = 1 section

36 sections = 1 township

## Volume

1728 cu. inches = 1 cubic foot

27 cu. feet = 1 cubic yard

## Troy Weight

24 grains = 1 pennyweight

20 pennyweights = 1 ounce (480 grains)

12 ounces = 1 pound (5760 grains)

## Apothecaries' Measures

60 minims = 1 fl.dram

8 fl.drams = 1 fl.ounce

16 fl.ounces = 1 pint

## Apothecaries' Weights

20 grains = 1 scruple

3 scruples = 1 dram

8 drams = 1 ounce (480 grains)

12 ounces = 1 pound (5760 grains)

As with the UK system these measures were originally defined by physical standard measures - the yard, the pound, the gallon and the bushel. They are now all defined by reference to the S I measures of the metre, the kilogram and the litre. These equivalent measures are exact.

1 yard = 0.9144 metres - same as UK

1 pound = 0.453 592 37 kilograms - same as UK

1 gallon (liquid) = 3.785 411 784 litres

1 bushel = 35.239 070 166 88 litres

Note particularly that the US gallon is a different size to the UK gallon so that NO liquid measures of the same name are the same size in the US and UK systems.

Also that the ton(US) is 2000 pounds while a ton(UK) is 2240 pounds. These are also referred to as a short ton and long ton respectively.

Note than in matters concerned with land measurements, for the most accurate work, it is necessary to establish whether the US survey measures are being used or not.