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acre to square kilometre

Live acre (ac) to square kilometre (km²) converter. Plus a 10-value reference table and FAQs.

From ac

acre

To km²

square kilometre

1 ac = 0.004km²

Conversion table

Ten sample values from acre to square kilometre. Use the converter above for arbitrary values.

acre (ac)	→	square kilometre (km²)
0.001 ac	→	4.0469e-6 km²
0.01 ac	→	4.0469e-5 km²
0.1 ac	→	0.000405 km²
0.5 ac	→	0.002023 km²
1 ac	→	0.004047 km²
2 ac	→	0.008094 km²
5 ac	→	0.020234 km²
10 ac	→	0.040469 km²
100 ac	→	0.404686 km²
1,000 ac	→	4.046856 km²

About the acre

4,047 m². US farmland and lot size.

About the square kilometre

100 hectares or 1,000,000 m². Country/city size.

How acre to square kilometre conversion works

Both units belong to Area. Unitbox first expresses the input in the category reference unit (m²), then expresses that same quantity in square kilometre.

The right unit depends on the convention used by your industry, country, instrument, or source document.

Reference value1 ac = 0.00404686 km²

CalculationBrowser-side, using Unitbox's shared unit data

Review noteFor safety-critical work, verify against the governing standard or instrument manual.

Unit definitions and conversion factors are maintained in the Unitbox methodology. Last reviewed with the current conversion dataset.