Acre to Square Kilometer Converter
Area · unit-converter
Convert Acre to Square Kilometer with a fixed input and output unit, step-by-step formula line, and reference tables. All calculations use square-meter-based definitions (international feet / yard standards, acre, hectare, and regional units like pyeong/tsubo).
Calculator
From: Acre (ac)
To: Square Kilometer (km2)
About Acre
The international acre is 4,046.8564224 m² by definition. Acres are standard for rural and suburban land in the US and still appear in UK property contexts.
About Square Kilometer
The square kilometer is a metric unit equal to one million square meters. It is standard for city sizes, large properties, and regional planning in metric countries.
How to convert acres to square kilometers
1 acre is equal to 0.0040468564224 square kilometer:
1 ac = (4046.8564224 m² ÷ 1000000 m²) km2 = 0.0040468564224 km2
Each acre is defined as 4046.8564224 m² and each square kilometer as 1000000 m², so one ac equals 4046.8564224 ÷ 1000000 km2 = 0.0040468564224 km2.
Let a(ac) be the numeric value of the same area measured in Acre (ac), and a(km2) the value in Square Kilometer (km2). Then:
a(km2) = a(ac) × (4046.8564224 / 1000000)
Equivalently, divide by how many ac fit into one km2 (m² per km2 divided by m² per ac):
a(km2) = a(ac) ÷ 247.10538146716533
Or: square kilometer = acre ÷ 247.10538146716533
Examples
Example #1: Convert 20 ac to square kilometer
20 ac = 20 ac × (4046.8564224/1000000) km2 = 0.0809371284 km2
20 ac = 20 ac ÷ 247.10538146716533 = 0.0809371284 km2
Example #2: Convert 50 ac to square kilometer
50 ac = 50 ac × (4046.8564224/1000000) km2 = 0.2023428211 km2
50 ac = 50 ac ÷ 247.10538146716533 = 0.2023428211 km2
Summary
To convert Acre to Square Kilometer, multiply the value in ac by the ratio of square meters per ac divided by square meters per km2. Equivalently: value_km2 = value_ac × (4046.8564224 / 1000000). Numerically, 1 ac equals 0.0040468564224 km2.
Relationship context
You are converting between US customary / imperial (Acres) and metric (SI) (Square Kilometers). Metric area is decimal from the square meter; US/imperial units use feet, yards, miles, and acres tied to international feet (0.3048 m) and related definitions. The numeric factor used here is 4.046856e-3.
Conversion tables
| Acre (ac) | Square Kilometer (km2) |
|---|---|
| 0.1 | 0.0004046856 |
| 1 | 0.0040468564 |
| 2 | 0.0080937128 |
| 3 | 0.0121405693 |
| 4 | 0.0161874257 |
| 5 | 0.0202342821 |
| 6 | 0.0242811385 |
| 7 | 0.028327995 |
| 8 | 0.0323748514 |
| 9 | 0.0364217078 |
| Acre (ac) | Square Kilometer (km2) |
|---|---|
| 10 | 0.0404685642 |
| 20 | 0.0809371284 |
| 30 | 0.1214056927 |
| 40 | 0.1618742569 |
| 50 | 0.2023428211 |
| 60 | 0.2428113853 |
| 70 | 0.2832799496 |
| 80 | 0.3237485138 |
| 90 | 0.364217078 |
| 100 | 0.4046856422 |