Unit converter

Acres to hectares.

Convert ac to ha and ha to ac. Type in either box and the other follows. UK land is registered in hectares and still talked about in acres; an acre is 0.404686 ha.

From

ac → haExact definition

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Display precision

Acres to hectares — common values, to 6 significant figures.
ac	ha
0.25 ac	0.101171 ha
0.5 ac	0.202343 ha
1 ac	0.404686 ha
2 ac	0.809371 ha
3 ac	1.21406 ha
5 ac	2.02343 ha
10 ac	4.04686 ha
20 ac	8.09371 ha
50 ac	20.2343 ha
100 ac	40.4686 ha

1 ac = 0.4046856422 ha

1 ha = 2.471053815 ac

Conversion goes through m² in both directions, so neither figure is rounded on the way.

Definitions

The acre is 4046.856 4224 m², historically the area one ox team could plough in a day. There are 640 acres in a square mile.
The hectare is 10 000 m² — a square 100 m on a side, and the metric unit of land area.
This conversion is exact by definition. 1 ac = 0.4046856422 ha.
Area is converted through m².

How it works

One direction multiplies and the other divides by the same number, so nothing is lost by going back and forth.

The value passes through m², the unit every other area unit on the site is defined against, rather than a number written into this page on its own. That is why the figure here, the figure in the table above and the general area converter always agree.

Display precision limits significant figures rather than decimal places, because one fixed number of decimals is useless across a range this wide. Very large and very small results switch to scientific notation with a proper superscript exponent. The editable box always holds a plain number at full working precision, so you can carry on from either side.

Common questions this answers: how many hectares in an acre (0.404686), how many acres in a hectare (2.47105), and what 5 ac is in hectares (2.02343 ha).

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