Unit converter

Acres to Hectares (acres to ha)

Multiply acres by 0.40468564224 to get hectares. That factor is exact, because the international acre is defined as 4,046.8564224 m². 100 acres is 40.47 ha and a 640-acre square mile is 259 ha.

Convert acres to hectares

acres to hectares

100 ac = 40.4686 ha

1 ac = 0.404686 ha · 1 ha = 2.47105 ac

Show the math

ha = ac × 0.40468564224

Uses exact legal definitions; results are rounded to 6 significant figures for display.

How to convert acres to hectares

ha = ac × 0.40468564224

One acre is exactly 0.40468564224 hectares, so multiply by 0.40468564224.

Worked example: converting 100 ac:

ha = ac × 0.40468564224
100 ac × 0.40468564224 = 40.4686 ha

Acres to hectares conversion table

Common values, each computed with the exact formula and rounded to 6 significant figures.

Acres (ac) to Hectares (ha)
Acres (ac)	Hectares (ha)
0.25 ac	0.101171 ha
0.5 ac	0.202343 ha
1 ac	0.404686 ha
2 ac	0.809371 ha
2.5 ac	1.01171 ha
5 ac	2.02343 ha
10 ac	4.04686 ha
20 ac	8.09371 ha
25 ac	10.1171 ha
40 ac	16.1874 ha
50 ac	20.2343 ha
80 ac	32.3749 ha
100 ac	40.4686 ha
160 ac	64.7497 ha
200 ac	80.9371 ha
250 ac	101.171 ha
320 ac	129.499 ha
500 ac	202.343 ha
640 ac	258.999 ha
1,000 ac	404.686 ha
2,000 ac	809.371 ha
5,000 ac	2,023.43 ha
10,000 ac	4,046.86 ha

Quick reference: everyday acres in hectares

One acre
1 ac = 0.404686 ha
A 'forty' (quarter-quarter section)
40 ac = 16.1874 ha
A quarter section
160 ac = 64.7497 ha
One section (one square mile)
640 ac = 258.999 ha
A 1,000-acre farm
1,000 ac = 404.686 ha

US land survey units in hectares

Much of the US west of the original colonies was surveyed into the Public Land Survey System's townships and sections. A section is one square mile, 640 acres or 259 ha. A quarter section is 160 acres (64.75 ha), and a 'forty' (a quarter of a quarter section) is 40 acres (16.19 ha). These sizes still shape farm boundaries and rural roads.

When international buyers, lenders or researchers compare US farmland with land elsewhere, they convert acreage to hectares. A 1,000-acre farm is 404.7 ha. Give hectares to one decimal place for land, which is a resolution of 1,000 m².

Converting per-acre rates and yields

Rates applied per acre have to be multiplied by 2.471 to become per-hectare rates, because a hectare holds 2.471 acres. A seeding or application rate written per acre therefore becomes about two and a half times larger per hectare. Converting the area alone without converting the rate is a common error on spray and seed calculations.

For quick percentage comparisons between yields or prices in the two units, the percentage calculator helps once both are on the same basis. To measure a plot's area from its sides first, use the square footage calculator.

Frequently asked questions

How many hectares is one acre?

One acre is 0.4047 hectares, exactly 0.40468564224 ha. Put another way, an acre is about 40% of a hectare, or roughly a square 63.6 m on each side. For small areas, square meters are often clearer: one acre is 4,046.86 m².

What's a fast mental conversion for acres to hectares?

Multiply by 0.4, which is the same as dividing by 2.5. 100 acres comes out as 40 ha, against an exact 40.47 ha. The shortcut is about 1.2% low, fine for picturing a farm but not for a deed. Multiplying by 0.405 gets you within 0.1%.

Does the US survey acre change the conversion?

Only in the sixth or seventh significant figure. The survey acre was about 4 parts per million larger than the international acre, which is less than 0.02 m² per acre. NIST retired the survey foot it was based on at the end of 2022, and modern conversions use the international acre, as this one does.