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Symbol:  ac, acre 
Category:  Area 
SI Equivalent:  4046.86 m2
Dimension L2 
System:  UK, US, CAN 
British unit of area used in surveyor's measurements. This is the English statute acre, and the US statute acre is the same. The acre was first defined in England in the reign of Edward I and is thought to be the area which a yoke of oxen could plow in a day. The acre was limited to its present definite quantity by statutes of Edward I, Edward III, and Henry VIII.
1 acre =1/640 square mile
  =4 roods
  =10 square chains (Gunter's)
  =160 square rods
  =4840 square yards
Convert     ac, acre  
1 ac, acre =
  Symbol Unit Name
40.4686  a  are 
4.04686×1031  b  barn 
1.03445×104  bbl (US, liq.)/ft  barrel (US, liq.) per foot 
862.041  bbl (US, liq.)/in  barrel (US, liq.) per inch 
7758.37  bbl (US, petrol)/ft  barrel (US, petrol) per foot 
646.531  bbl (US, petrol)/in  barrel (US, petrol) per inch 
4046.86    centare 
7.98657×106  cin  circular inch 
7.98657×1012  cmil  circular mil 
0.404686  ha  hectare 
0.490864    morgen (Dutch) 
1.59813    morgen (Prussian) 
0.472471    morgen (South Africa) 
6.25×10-3    quarter section 
  rood (UK) 
1.5625×10-3  sq.mi, mi2 (stat.)  section (square statute mile) 
4.04686×1055    shed 
4.04686×107  cm2  square centimeter 
4.356  sq. ch. (engineer's)  square chain (engineer's) 
10  sq. ch. (Gunter's)  square chain (Gunter's) 
40.4686  dam2  square decameter 
4.04686×105  dm2  square decimeter 
4.04686×10-33  Em2  square exameter 
4.04686×1033  fm2  square femtometer 
4.04686×1033  f2  square fermi 
4.356×104  ft2  square foot 
4.04686×10-15  Gm2  square gigameter 
0.404686  hm2  square hectometer 
6.27264×106  in2, sq. in  square inch 
4.04686×10-3  km2  square kilometer 
4.04686×10-9  Mm2  square megameter 
4046.86  m2  square meter 
4.04686×1015  ┬Ám2  square micrometer 
6.27264×1012  mil2  square mil (thou) 
7.34723×10-5  sq. mi. (geogr.)  square mile (geographical) 
1.17987×10-3  sq. mi. (int. naut.)  square mile (int. naut.) 
1.56249×10-3  sq. mi. (int.)  square mile (int.) 
4.04686×109  mm2  square millimeter 
4.04686×1021  nm2  square nanometer 
159.999  rd2  square perch 
4.04686×10-27  Pm2  square petameter 
4.04686×1027  pm2  square picometer 
159.999  rd2  square pole 
159.999  rd2  square rod 
4.04686×10-21  Tm2  square terameter 
4840  yd2, sq. yd  square yard 
4.04686×1051  ym2  square yoctometer 
1.18926×10-35  Ym2  square yottameter 
4.04472×1045  zm2  square zeptometer 
1.18926×10-35  Zm2  square zettameter 
4.34028×10-5    township (US) 
2.25    vergee (Jersey) 
2.625    vergees (Guernsey) 
Fuel Consumption
  Symbol Unit Name
1.7205×109  gal/mile  gallon per mile 
4.04686×1011  l/100 km  liter per 100 kilometers 
4.04686×109  l/km  liter per kilometer 
Hydrodynamic permeability
  Symbol Unit Name
4.10048×1015    darcy