Updated May 24, 2026

Acres to Square Kilometers Converter

Multiply acres by 0.00404686 to get square kilometers. 1 acre = 0.00405 km². For example, 100 acres = 0.405 km² and 640 acres = 2.59 km².

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Common Conversions

Key Takeaways

  • 1 acre = 0.00404686 km². Multiply acres by 0.00404686.
  • 247.105 acres = 1 km².
  • 640 acres = 2.59 km² = 1 square mile.
  • 100 acres = 0.405 km².
  • 1,000 acres = 4.047 km².

How Do You Convert Acres to Square Kilometers?

Multiply acres by 0.00404686 to get square kilometers. The formula is: km² = Acres x 0.00404686. Since 1 acre = 4,046.86 m² and 1 km² = 1,000,000 m², dividing gives the conversion factor.

Sam Okafor prepares an international listing for a 320-acre ranch. Converting: 320 x 0.00404686 = 1.295 km². He includes both measurements in the listing to appeal to both American and international buyers. The property is roughly 1.14 km x 1.14 km if square shaped.

Farm and Ranch Size Reference

Acres km² Classification
1 ac0.00405 km²Residential lot
5 ac0.0202 km²Hobby farm
40 ac0.162 km²Small farm
160 ac0.647 km²Quarter section (homestead)
320 ac1.295 km²Half section
640 ac2.590 km²Full section (1 mi²)
2,500 ac10.117 km²Large ranch
10,000 ac40.469 km²Industrial farm

Practical Applications

International Land Sales

Sam Okafor works with a European investment group looking at ranch land. They are used to thinking in square kilometers. A 2,500-acre ranch = 10.12 km² = 1,012 hectares. He compares it to familiar European references: about the size of a small town or 1,420 soccer fields. The investors appreciate having metric comparisons.

Environmental Reports

Tom Brewer reviews a wetland survey. The protected area covers 850 acres = 3.44 km². Scientific papers report areas in km², so his grant application describes "3.44 km² of protected riparian habitat." The buffer zone adds another 200 acres (0.81 km²), bringing the total conservation area to 1,050 acres (4.25 km²).

Municipal Planning

Dana Kowalski reviews zoning maps for Pinewood Falls. The town covers about 8,500 acres = 34.4 km². Residential zones account for 3,200 acres (12.95 km²), commercial zones 450 acres (1.82 km²), and parks 1,100 acres (4.45 km²). She uses km² in presentations to the planning board because the numbers are more compact and easier to compare.


Related Calculators

Frequently Asked Questions

How many square kilometers is 1 acre?

One acre equals 0.00404686 square kilometers. You need about 247 acres to make 1 square kilometer.

How do I convert acres to square kilometers?

Multiply acres by 0.00404686 to get square kilometers. For example, 100 ac = 0.405 km², 500 ac = 2.023 km², and 1,000 ac = 4.047 km².

How many acres is 1 square kilometer?

One square kilometer = 247.105 acres. A square kilometer is a large area: 1,000 m x 1,000 m = 1,000,000 square meters.

How many square kilometers is 640 acres?

640 acres = 2.59 km² = 1 square mile. The number 640 comes from the original US land survey system where each section was 1 square mile = 640 acres.

How many acres are typical farms?

The average US farm is about 445 acres = 1.80 km². Small hobby farms are 5-50 acres (0.02-0.20 km²). Large commercial operations can exceed 10,000 acres (40.47 km²).