An acre is an area measurement that was originally defined by how much land an ox could plough in one day.[1] Today the definition of an acre is standardized, so that it is easy to convert between acres and other units used to measure area, such as square miles (mi²). The Internet has numerous calculators that will make this conversion for you, but most teachers will require you to show your work, or you may be looking for an explanation of the actual steps involved. Luckily it is easy to calculate the conversion yourself using division or multiplication.

Method 1
Method 1 of 2:

Using Division

  1. 1
    Understand that there are 640 acres in one square mile.[2] Both units are different ways to measure area.
    • By definition a square miles is square, but an acre can be any shape.[3]
  2. 2
    Determine how many acres you are converting to square miles. This number will probably already be given to you, but you can also use an area calculator map to determine the acreage of a real-world tract of land.[4]
    • For example, you might want to convert 2,500 acres to square miles.
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  3. 3
    Divide the number of acres by 640.[5] Each 640 acres equals 1 square mile, so you need to determine how many times 640 goes into the number of acres to determine how many square miles.
    • You can divide using a calculator, or, if you’re feeling ambitious, by hand.
    • For example, to convert 2,500 acres into square miles, you would calculate .
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Method 2
Method 2 of 2:

Using Multiplication

  1. 1
    Understand that there are 640 acres in one square mile.[6] Both units are different ways to measure area.
    • By definition a square miles is square, but an acre can be any shape.[7]
  2. 2
    Determine how many acres you are converting to square miles. This number will probably already be given to you, but you can also use an area calculator map to determine the acreage of a real-world tract of land.[8]
    • For example, you might want to convert 2,500 acres to square miles.
  3. 3
    Multiply the number of acres by .[9] This decimal is a way of representing the ratio of square miles to acres, or , since, for every 1 square mile you have, you have 640 acres. To put it another way, each acre is 0.0015625 of a mile.
    • The decimal comes from dividing 1 by 640. So, you could also multiply by .
    • You can multiply using a calculator, or, if you’re feeling ambitions, by hand.
    • For example, to convert 2,500 acres into square miles, you would calculate .
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Community Q&A

  • Question
    How many hectares are in an acre?
    Donagan
    Donagan
    Top Answerer
    A hectare is actually the larger measurement. One acre is the equivalent of approximately 4/10 of a hectare. A hectare is 2.47 acres.
  • Question
    How many steps are in a mile?
    Donagan
    Donagan
    Top Answerer
    Approximately 2,000, depending on the length of the steps.
  • Question
    How many square miles in 26,000 acres?
    Donagan
    Donagan
    Top Answerer
    Divide acres by 640 to find square miles. In this case, 26,000 ÷ 640 = 40.625 sq mi.
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wikiHow Staff
Co-authored by:
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This article was co-authored by wikiHow Staff. Our trained team of editors and researchers validate articles for accuracy and comprehensiveness. wikiHow's Content Management Team carefully monitors the work from our editorial staff to ensure that each article is backed by trusted research and meets our high quality standards. This article has been viewed 56,935 times.
21 votes - 71%
Co-authors: 13
Updated: March 29, 2019
Views: 56,935
Categories: Conversion Aids
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