Area conversion

Convert Acre to Square kilometer

1 acre (ac) equals 0.004046856422 square kilometer (km²). Enter any value below to convert from ac to km².

Enter a value and choose units. Results update instantly.

1 ac = 0.0040468564 km²

All Area units

From 1 ac
UnitValue
Square meter m² 4,046.8564224
Square kilometer km² 0.0040468564
Square centimeter cm² 40,468,564.2239999995
Square millimeter mm² 4,046,856,422.4000005722
Square inch in² 6,272,640
Square foot ft² 43,560
Square yard yd² 4,840
Square mile mi² 0.0015625
Acre ac 1
Hectare ha 0.4046856422
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Formula

ac to km² conversion formula

Use this relationship for a direct conversion:

km² = ac x 0.004046856422

Worked example

2 ac = 0.0080937128 km².

Values derived from exact metric and international length definitions.

Quick reference

Acre to Square kilometer table

Acre (ac)Square kilometer (km²)
0.010.0000404686
0.10.0004046856
10.0040468564
20.0080937128
50.0202342821
100.0404685642
250.1011714106
500.2023428211
1000.4046856422
1,0004.0468564224

From unit

About the acre

Exactly 43,560 square feet.

Symbol: ac

To unit

About the square kilometer

One million square meters.

Symbol: km²

Keep converting

Related conversions

Square kilometer to AcreReverse this conversion Acre to Square meterac to m²Acre to Square footac to ft²Acre to Square inchac to in²Acre to Square yardac to yd²Acre to Square mileac to mi²Acre to Hectareac to ha

Source

Conversion standard

Definitions are checked against NIST SP 811: Area units. Calculations use full internal precision before display rounding.

View the complete area converter

Questions

ac to km² FAQ

How do you convert acre to square kilometer?

Use the formula km² = ac x 0.004046856422. 1 acre (ac) equals 0.004046856422 square kilometer (km²).

Is the ac to km² conversion exact?

Both unit definitions use exact factors. Only the displayed decimal may be rounded.