Convert acres to square kilometers

1 ac=0.004047km²

Use the converter below to change any acres value into square kilometers instantly — with formula, conversion table, and real-world examples.

You have

Equals

0.0040469

Conversion formula

Forward

square kilometers = acres × 0.004047

Reverse

acres = square kilometers × 247.105

Example: 10 ac × 0.004047 = 0.04047 km².

About both units

From

Acre

The acre equals 4046.86 square metres — originally the area a team of oxen could plough in a day. It is the standard rural land unit in the US, UK and Canada. Suburban American lots are typically a quarter to half an acre. 640 acres equal one square mile.

Real-world: A US suburban lot is 0.25–0.5 acre. A standard UK rural property might be 5 acres. A football pitch is about 1.8 acres.

Read full acre reference →

Square Kilometer

km²

The square kilometre equals 1,000,000 m² or 100 hectares. It is used for city, region and country areas. Greater London is about 1572 km². The smallest sovereign countries (Monaco, Vatican City) are under 3 km² each.

Real-world: Greater London is 1572 km². France is 643,801 km². The Serengeti National Park is 14,763 km².

Read full square kilometer reference →

Acre to Square Kilometer conversion table

Common acres to square kilometers values for quick reference.

Acre (ac)	Square Kilometer (km²)
1 ac	0.004047 km²
5 ac	0.02023 km²
10 ac	0.04047 km²
50 ac	0.2023 km²
100 ac	0.4047 km²
500 ac	2.02343 km²
1,000 ac	4.04686 km²
5,000 ac	20.2343 km²
10,000 ac	40.4686 km²
50,000 ac	202.343 km²

Tips & common mistakes

Quick tips

1 acre = 43,560 ft² = 0.4047 ha.
640 acres = 1 square mile — a "section" in US land survey.
An acre is 43,560 ft² — a useful number for US real-estate calculations.

Avoid these

Using "acre" in modern European property — use hectares or m² instead.
Assuming an acre is a specific shape — it is only an area (any shape).
Multiplying acres by 4000 m² — correct value is 4046.86.

Frequently asked questions

How many square kilometers in a acre?

One acre equals 0.004047 square kilometers.

How do I convert acres to square kilometers?

Multiply the acre value by 0.004047 to get the equivalent in square kilometers.

What is 100 acres in square kilometers?

100 acres equals 0.4047 square kilometers.

Is a acre bigger than a square kilometer?

No. 1 acre equals 0.004047 square kilometers, so one acre is smaller.

How to convert acres to square kilometers without a calculator?

Multiply by 0 for a quick estimate; use a calculator for precise results.

Related area conversions

📊 See full comparison matrix →

Conversions in other categories

WeightKilogram → Pound LengthKilometer → Mile TemperatureCelsius → Fahrenheit VolumeLiter → US Gallon SpeedKilometer per Hour → Mile per Hour EnergyKilojoule → Kilocalorie PressureBar → Pound per Square Inch PowerKilowatt → Mechanical Horsepower