Text and photographs copyright of Jim Shead. 

Imperial Weights and Measures
Imperial Weights, Measures and Currency
The following is provided for people reading historic documents who are not familiar with British measures and terms, many of which have long ceased to be used.
Measures of Length
Unit  Equal to  Metric equivalent 
1 inch    25.4 mm 
1 foot  12 inches  304.8 mm 
1 yard  3 feet  914.4 mm 
1 pole, rod or perch  5½ yards  5.0292 m 
1 chain  4 poles  20.1168 m 
1 furlong  10 chains  201.168 m 
1 mile  8 furlongs (1,760 yards)  1.6093 km 
1 league  3 miles  4.8279 km 
Nautical Measures of Length
Unit  Equal to  Metric equivalent 
1 fathom  6 feet  1.8288 m 
1 cable  608 feet  185.3184 m 
1 nautical mile  10 cables  1.852 km 
Measures of Area
Unit  Equal to  Metric equivalent 
square inch    6.4516 cm^{2} 
square foot  144 square inches  0.0929 m^{2} 
square yard  9 square feet  0.8361 m^{2} 
square pole  30¼ square yards  25.292 m^{2} 
rood  40 square poles  1,011.725 m^{2} 
acre  4 roods  4046.9 m^{2} 
square mile  640 acres  2.59 km^{2} 
Measures of Weight
Unit  Equal to  Metric equivalent 
ounce    28.35 grams 
pound  16 onces  0.4536 kg 
stone  14 pounds  6.3503 kg 
quarter  28 pounds  12.7 kg 
cental  100 pounds  45.36 kg 
hundredweight  4 quarters or 112 pounds  50.802 kg 
short ton  2,000 pounds  907.2 kg 
ton  20 hundredweights or 2240 pounds  1.016 tonne 
Measures of Capacity
Unit  Equal to  Metric equivalent 
fluid ounce    28.413 millilitres 
gill  5 fluid ounces  0.1421 litres 
pint  4 gills or 20 fluid ounces  0.5683 litres 
quart  2 pints  1.1365 litres 
gallon  4 quarts  4.546 litres 
peck  2 gallons  9.0922 litres 
bushel  4 pecks  36.3686 litres 
quarter  8 bushels  290.949 litres 
load  5 quarters  1,454.745 litres 
chaldron  36 bushels  1,309.2696 litres 
Units of Currency
Note: this table refers to the British Currency prior to 15th February 1971 when the UK converted to decimal currency. After this date the pound was divided into 100 pence and currency values were displayed as, for example, £2.22 or as 23p for amounts less than a pound. Amounts using the "p" for pence always refer to post decimalisation pence. Before decimalisation pence amounts were indicated by the letter "d" and amounts were usually given in the form £3 7s 6d i.e. 3 pounds 7 shillings and 6 (old) pence.
Unit  Equal to  Pounds sterling equivalent 
farthing  ¼ of a penny  £0.0010416 
halfpenny or ha'penny  ½ of a penny  £0.0020833 
penny  a 240th part of a pound  £0.0041666 
groat  4 pence  £0.016666 
shilling  12 pence  £0.05 
florin  2 shillings  £0.1 
halfcrown  2 shiilings and 6 pence  £0.125 
crown  5 shillings  £0.25 
sovereign  A gold £1 coin  £1 
guinea  Originally a gold coin worth 21 shillings  £1.05 
  
Text and photographs copyright of Jim Shead. 
