In order to convert square feet to acres, first you need to know how many square feet there are in an acre. By definition 1 acre is equal to 43560 square feet.

Study the example in the figure below carefully. It shows how to convert 130680 square feet to acres.

As you can see from the example below, 1 acre is equal to 43560 square feet. This relationship between square feet and acres can help you convert any area that is in square feet to acres.

**Example #1**

Convert 87120 square feet to acres.

We can solve this problem by setting up a proportion the exact same way it is demonstrated in the example in the figure above.

"If" 43560 square feet is equal 1 acre,

"then" 87120 square feet is equal to x acres.

Here is table that summarizes this problem.

43560 | 1 acre |

87120 | x |

The proportion is 43560 / 87120 = 1 acre / x

After cross multiplication, we get 43560 × x = 87120 × 1 acre

43560x = 87120 acres

x = 87120 acres / 43560

x = 2 acres

87120 square feet is equal to 2 acres.

Notice how we put the numbers in the table in the same order as they were in the "if-then" sentence. It is very important to pull out the numbers in the same order!

Your "if-then" sentence could have been instead what you see below.

"If" 1 acre is equal 43560 square feet,

"then" x acres is equal to 87120 square feet

Your table will then look a little bit different as you pull out the numbers. However, you will still get the same answer when you set up the proportion and solve it.

1 acre | 43560 |

x | 87120 |

**Example #2**

Convert 21780 square feet to acres.

Again, this problem can be solved by setting up a proportion.

"If" 43560 square feet is equal 1 acre

"then" 21780 square feet is equal to x acres

Here is table that summarizes this problem.

43560 | 1 acre |

21780 | x |

The proportion is 43560 / 21780 = 1 acre / x

After cross multiplication, we get 43560 × x = 21780 × 1 acre

43560x = 21780 acres

x = 21780 acres / 43560

x = 0.5 acres

21780 square feet is equal to 0.5 acres.