Convert Acres to Square Kilometers

Enter the area in acres below to get the value converted to square kilometers.

Results in Square Kilometers:
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1 ac = 0.004047 sq km

How to Convert Acres to Square Kilometers

Calculators can be used to convert measurements from one unit to another

To convert a acre measurement to a square kilometer measurement, multiply the area by the conversion ratio. One acre is equal to 0.004047 square kilometers, so use this simple formula to convert:

square kilometers = acres × 0.004047

The area in square kilometers is equal to the acres multiplied by 0.004047.

For example, here's how to convert 5 acres to square kilometers using the formula above.
5 ac = (5 × 0.004047) = 0.020234 sq km

Acres and square kilometers are both units used to measure area. Keep reading to learn more about each unit of measure.


One acre is defined as the area equal to a space that is one chain (66 ft) by one furlong (660 ft), or 10 square chains. That's equal to 43,560 square feet for those unfamiliar with those units of measure.

The acre is a US customary and imperial unit of area. Acres can be abbreviated as ac, for example 1 acre can be written as 1 ac.

Try our acreage calculator to find the area of a plot of land in acres by locating the boundaries on a map.

Square Kilometers

One square kilometer is equal to the area of a square with sides that are 1 kilometer in length.

The square kilometer, or square kilometre, is a multiple of the square meter, which is the SI derived unit for area. In the metric system, "kilo" is the prefix for 103. A square kilometer is sometimes also referred to as a square km. Square kilometers can be abbreviated as sq km, and are also sometimes abbreviated as km². For example, 1 square kilometer can be written as 1 sq km or 1 km².

Acre Measurements and Equivalent Square Kilometer Conversions

Common acre values converted to the equivalent square kilometer value
Acres Square Kilometers
1 ac 0.004047 sq km
2 ac 0.008094 sq km
3 ac 0.012141 sq km
4 ac 0.016187 sq km
5 ac 0.020234 sq km
6 ac 0.024281 sq km
7 ac 0.028328 sq km
8 ac 0.032375 sq km
9 ac 0.036422 sq km
10 ac 0.040469 sq km
11 ac 0.044515 sq km
12 ac 0.048562 sq km
13 ac 0.052609 sq km
14 ac 0.056656 sq km
15 ac 0.060703 sq km
16 ac 0.06475 sq km
17 ac 0.068797 sq km
18 ac 0.072843 sq km
19 ac 0.07689 sq km
20 ac 0.080937 sq km
21 ac 0.084984 sq km
22 ac 0.089031 sq km
23 ac 0.093078 sq km
24 ac 0.097125 sq km
25 ac 0.101171 sq km
26 ac 0.105218 sq km
27 ac 0.109265 sq km
28 ac 0.113312 sq km
29 ac 0.117359 sq km
30 ac 0.121406 sq km
31 ac 0.125453 sq km
32 ac 0.129499 sq km
33 ac 0.133546 sq km
34 ac 0.137593 sq km
35 ac 0.14164 sq km
36 ac 0.145687 sq km
37 ac 0.149734 sq km
38 ac 0.153781 sq km
39 ac 0.157827 sq km
40 ac 0.161874 sq km

More Acre Area Conversions

US Customary
Convert to Square Miles
1 ac is equal to 0.001563 square miles
Convert to Square Yards
1 ac is equal to 4,840 square yards
Convert to Square Feet
1 ac is equal to 43,560 square feet
Convert to Square Inches
1 ac is equal to 6,272,640 square inches
SI Units
Convert to Square Meters
1 ac is equal to 4,046.86 square meters
Convert to Square Centimeters
1 ac is equal to 40,468,564.2 square centimeters
Convert to Square Millimeters
1 ac is equal to 4,046,856,422.4 square millimeters
Other Metric Units
Convert to Hectares
1 ac is equal to 0.404686 hectares
Convert to Ares
1 ac is equal to 40.468564 ares