# acre

This entry is about the unit of area. For other meanings see Acre (disambiguation)

The acre is a unit of area in a number of different systems, including the imperial and US customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre.

The area of one acre (red) overlaid on an American football field
One acre comprises 4,840 square yards or 43,560 square feet. Because of alternative definitions of a yard or a foot, the exact size of an acre also varies slightly. Traditionally, an acre was a swath of land one furlong long and one chain wide. A modern acre can have arbitrary dimensions as long as the area is correct. For example, a strip of land 1 inch wide and 99 miles long is also an acre.

The acre is often used to express areas of land. In the metric system, the hectare is commonly used for the same purpose. An acre is approximately 40% of a hectare.

One acre is 90.75 yards of a 53.33-yard-wide American football field. The full field, including the end zones, covers approximately 1.32 acres.

## International acre

In 1958, the United States and countries of the Commonwealth of Nations defined the length of the international yard to be 0.9144 meters.[1] Consequently, the international acre is exactly 4046.8564224 square meters.

## United States survey acre

The United States survey acre is approximately 4046.873 square meters; its exact value (404613,525,42615,499,969 m²) is based on an inch defined by 1 meter = 39.37 inches exactly, as established by the Mendenhall Order. It is the standard acre in the United States, but the fractional difference from the international acre is only 4 millionths, or 4 ten-thousandths of one percent.

## Equivalence to other units of area

1 international acre is equal to the following metric units:
1 United States survey acre is equal to:
1 acre (both variants) is equal to the following customary units:
• 66 feet × 660 feet (43,560 square feet)
• 4840 square yards
• 160 perches. A Perch is equal to a square rod (1 square rod is 0.00625 acre)
• 10 square chains
• 4 roods
• A chain by a furlong (chain 22 yards, furlong 220 yards)
• 0.0015625 square mile (1 square mile is equal to 640 acres)
1 international acre is equal to the following Indian unit:

## Historical origin

The word "acre" is derived from Old English æcer (originally meaning "open field", cognate to German Acker, Latin ager and Greek αγρος (agros).

The acre was selected as approximately the amount of land tillable by one man behind an ox in one day. This explains one definition as the area of a rectangle with sides of length one chain and one furlong. A long narrow strip of land is more efficient to plough than a square plot, since the plough does not have to be turned so often. The word "furlong" itself derives from the fact that it is one furrow long.

Statutory values for the acre were enacted in England by acts of:
Historically the size of farms and landed estates in the United Kingdom was always expressed in acres, even if the number of acres was so large that it might conveniently have been expressed in square miles. For example a certain landowner might have been said to own 32,000 acres of land, not 50 square miles of land.

## References

1. ^ National Bureau of Standards. Refinement of Values for the Yard and the Pound.

Acre may refer to:
• acre, a unit of land area measurement.
• Acre, Israel, the English name for the ancient city called Akko in Hebrew and Akka in Arabic.
• District of Acre, an administrative district of Palestine, between 1800 and 1948.

units of measurement have played a crucial role in human endeavour from early ages up to this day. Disparate systems of measurement used to be very common. Now there is a global standard, the International System (SI) of units, the modern form of the metric system.
Area is a physical quantity expressing the size of a part of a surface. The term Surface area is the summation of the areas of the exposed sides of an object.

### Units

Units for measuring surface area include:
square metre = SI derived unit

The square yard is an imperial/US customary (non-metric) unit of area, formerly used in most of the English-speaking world but now generally replaced by the square metre outside of the US.
The square foot is an Imperial unit / U.S. customary unit (non-SI non-metric) of area, used in the United States, United Kingdom and elsewhere. It is defined as the area of a square with sides of 1 foot (0.333...
1 furlong =
SI units
0 m 0 km
US customary / Imperial units
0 ft 0 yd
A furlong is a measure of distance within imperial units and U.S. customary units, and is equal to 660 feet or one-eighth of a mile. In metric units, this is 201.
1 chain =
SI units
0 m 0 cm
US customary / Imperial units
0 ft 0 yd

A chain is a unit of length; it measures 66 feet, which equates to 20.1168 metres). There are therefore 80 chains in one statute mile.
1 inch =
SI units
010−3 m 0 mm
US customary / Imperial units
010−3 ft 010−3 yd

An inch (plural: inches; symbol or abbreviation: in or, sometimes,
1 mile =
SI units
0 m 0 km
US customary / Imperial units
0 ft 0 yd

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A hectare (symbol ha, pronounced /ˌhɛkˈtɛə(ɹ)/) is a unit of area equal to 10,000 square metres, or one square hectometre, and commonly used for measuring land area.
American football, known in the United States simply as football [1] is a competitive team sport known for its physical roughness despite being a highly strategic game.
Motto
"In God We Trust"   (since 1956)
"E Pluribus Unum"   ("From Many, One"; Latin, traditional)
Anthem
(and largest city)
Official languages English
Membership 53 sovereign states
-  Head of the Commonwealth Queen Elizabeth II
1 yard =
SI units
0 m 0 mm
US customary / Imperial units
0 ft 0 in
A yard (abbreviation: yd) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary
1 metre =
SI units
1000 mm 0 cm
US customary / Imperial units
0 ft 0 in
The metre or meter[1](symbol: m) is the fundamental unit of length in the International System of Units (SI).
square metre (also spelled meter, see spelling differences) is the SI derived unit of area, with symbol m². It is defined as the area of a square whose sides measure exactly one metre.
square metre (also spelled meter, see spelling differences) is the SI derived unit of area, with symbol m². It is defined as the area of a square whose sides measure exactly one metre.
The Mendenhall Order marked a decision to change the fundamental standards of length and mass of the United States from the customary standards based on those of England to metric standards. It was issued on April 5, 1893 by Thomas Corwin Mendenhall, superintendent of the U.S.
Motto
"In God We Trust"   (since 1956)
"E Pluribus Unum"   ("From Many, One"; Latin, traditional)
Anthem
square metre (also spelled meter, see spelling differences) is the SI derived unit of area, with symbol m². It is defined as the area of a square whose sides measure exactly one metre.
A hectare (symbol ha, pronounced /ˌhɛkˈtɛə(ɹ)/) is a unit of area equal to 10,000 square metres, or one square hectometre, and commonly used for measuring land area.
square metre (also spelled meter, see spelling differences) is the SI derived unit of area, with symbol m². It is defined as the area of a square whose sides measure exactly one metre.
A hectare (symbol ha, pronounced /ˌhɛkˈtɛə(ɹ)/) is a unit of area equal to 10,000 square metres, or one square hectometre, and commonly used for measuring land area.
The square foot is an Imperial unit / U.S. customary unit (non-SI non-metric) of area, used in the United States, United Kingdom and elsewhere. It is defined as the area of a square with sides of 1 foot (0.333...
The square yard is an imperial/US customary (non-metric) unit of area, formerly used in most of the English-speaking world but now generally replaced by the square metre outside of the US.
perch is equal to a square rod. There are 160 perches to an acre (1 square rod is 0.00625 acres).

The metric conversion for a perch is 25.29 square metres

• Conversion of units
• Acre-foot

1 rod =
SI units
0 m 0 cm
US customary / Imperial units
0 ft 0 yd

The rod is a unit of length, equal to 5.5 yards, 11 cubits, 5.0292 metres, 16.
1 chain =
SI units
0 m 0 cm
US customary / Imperial units
0 ft 0 yd

A chain is a unit of length; it measures 66 feet, which equates to 20.1168 metres). There are therefore 80 chains in one statute mile.