How do you convert acres to square kilometers?

To convert acres (ac) to square kilometers (km²), multiply the area in acres by 0.00404685 (square kilometers = acres × 0.00404685).

What is 5 acres in square kilometers?

5 acres (5 ac) is equal to 0.02023 square kilometers (0.02023 km²).

Which is larger, 1 acre (ac) or 1 square kilometer (km²)?

One square kilometer (km²) is larger than one acre (ac). Specifically, 1 km² equals 247.10538 ac, while 1 ac is 0.00404685 km².

How do I convert back from square kilometers (km²) to acres (ac)?

To reverse the calculation from km² to ac, multiply your square kilometer value by the inverse factor 247.10538 (or divide by 0.00404685). You can also click the Swap button in the tool above to flip directions in one click.

Are there regional or standard differences when converting ac and km²?

International Foot vs. US Survey Foot: Under the 1959 International Yard and Pound Agreement, 1 international foot is defined as 0.3048 meters. Legacy US land deeds and State Plane Coordinate Systems prior to 2023 used the US Survey Foot (1200/3937 m ≈ 0.3048006096 m), a difference of 2 parts per million (about 0.01 ft per mile).

Acres to Square Kilometers Converter

Enter the area in acres below to convert it to square kilometers.

Square Kilometers to Acres (km² → ac)

Convert Acres to Square Kilometers

Enter a value in acres (ac) to convert to square kilometers (km²).

Value (ac)

From

Result

•

0.020234282square kilometers

5 ac = 0.020234282 km²

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Suggested Conversions

Reference:NIST OWM (SI Units — Length & Area)

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Acre to Square Kilometer Conversion Table

Table showing various acre measurements converted to square kilometers. Click any preset value or arrow to load it into the converter.

Acres (ac)	Square Kilometers (km²)
1 ac	0.0040469 km²
2 ac	0.0080937 km²
2.5 ac	0.0101171 km²
5 ac	0.0202343 km²
10 ac	0.0404686 km²
15 ac	0.0607028 km²
20 ac	0.0809371 km²
25 ac	0.1011714 km²
30 ac	0.1214057 km²
50 ac	0.2023428 km²

How to Convert Acres to Square Kilometers

To convert acres to square kilometers, multiply the area by the following conversion ratio: 0.0040469 square kilometers/acre.

Since one acre is equal to 0.0040469 square kilometers, you can use this simple formula to convert:

square kilometers = acres × 0.0040469

The area in square kilometers is equal to the area in acres multiplied by 0.0040469.

For example, here's how to convert 5 acres to square kilometers using the formula above.

square kilometers = (5 ac × 0.0040469) = 0.0202343 km²

How Many Square Kilometers Are in an Acre?

There are 0.0040469 square kilometers in an acre, which is why we use this value in the formula above.

1 ac = 0.0040469 km²|1 km² = 247.1053815 ac

Our acre to square kilometer calculator automatically converts your area measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.

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

What Is an Acre?

An acre is a unit of area equal to 4,046.8564224 square meters (m²), the base unit for area. Imperial & US Customary land unit equal to 43,560 square feet. [1]

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

When working with acres (ac) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.

In practice, acres (ac) are widely used across large-scale industrial, bulk, and macro-level area specifications within US customary and imperial workflows, engineering documentation, and technical data sheets.

Learn more about acres in our Area Converter.

What Is a Square Kilometer?

A square kilometer is a unit of area equal to 1,000,000 square meters (m²), the base unit for area. Equal to 1,000,000 square meters or 100 hectares. [2]

The square kilometer is classified as an International System of Units (SI) unit of area. Square Kilometers can be abbreviated as km²; for example, 1 square kilometer can be written as 1 km².

When working with square kilometers (km²) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.

In practice, square kilometers (km²) are widely used across large-scale industrial, bulk, and macro-level area specifications within International System of Units (SI) workflows, engineering documentation, and technical data sheets.

Learn more about square kilometers in our Area Converter.

When converting area between acres (ac) and square kilometers (km²), keep full floating-point precision (1 ac = 0.0040469 km²; 1 km² = 247.1053815 ac) during intermediate calculations and round only the final square kilometer figure to match your instrument tolerance.

More Acre & Square Kilometer Conversions

Need to calculate in the opposite direction? Use our square kilometers to acres calculator to switch your starting unit immediately. You can also explore related tools such as converting square kilometers to acres, converting square miles to square kilometers, or converting acres to hectares.

Convert from Acres

Convert to Square Kilometers

Frequently Asked Questions

There are 0.00404685 square kilometers (km²) in 1 acre (ac). Conversely, 1 square kilometer (km²) is equal to 247.10538 acres (ac).

Area Converter

Quick Info

Direct Factor: 1 acre (ac) equals 0.00404685 square kilometers (km²).
Inverse Factor: 1 square kilometer (km²) equals 247.10538 acres (ac).
Formula: square kilometers = acres × 0.00404685.
Standard Note: International Foot vs. US Survey Foot: Under the 1959 International Yard and Pound Agreement, 1 international foot is defined as 0.3048 meters. Legacy US land deeds and State Plane Coordinate Systems prior to 2023 used the US Survey Foot (1200/3937 m ≈ 0.3048006096 m), a difference of 2 parts per million (about 0.01 ft per mile).

Units Comparison

Acre (ac)

Imperial & US Customary land unit equal to 43,560 square feet.

Square Kilometer (km²)

Equal to 1,000,000 square meters or 100 hectares.

Square Meter (m²)

SI derived unit of surface area.

References

[1]NIST OWM · SI Units — Length & Area
Source
[2]NIST HB 44 · Acre, Hectare & Land Survey Tables
Source
[3]NIST SP 811 · NIST SP 811 App. B.9 (Area)
Source

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References

NIST · BIPM · ISO

[1]
NIST OWM (SI Units — Length & Area)·Area Metrology Standard — Acres (ac) to Square Kilometers (km²)
NIST OWM Standard
[2]
NIST HB 44 (Acre, Hectare & Land Survey Tables)·Unit Specifications: Acre (ac) & Square Kilometer (km²)
NIST HB 44 Specification
[3]
NIST SP 811 (NIST SP 811 App. B.9 (Area))·Conversion Factors & Mathematical Basis (ac to km²)
NIST SP 811 Reference

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