Acres to Hectares Calculator

How the acres to hectares conversion works

An acre is a US customary and imperial unit of area; a hectare is a metric unit equal to 10,000 square meters. The two are linked by a fixed, defined factor: one international acre equals exactly 0.40468564224 hectares. Enter an area in acres and the calculator multiplies it by that factor, then derives the equivalent in square meters and square feet. Nothing here is an estimate — the conversion is exact, and the only figure that carries uncertainty is the acreage entered.

The exact conversion factor

The acre is defined as one chain by one furlong — 66 ft × 660 ft = 43,560 square feet. Because a foot is defined as exactly 0.3048 m, a square foot is exactly 0.09290304 m², so 43,560 ft² equals exactly 4,046.8564224 m². Dividing that by 10,000 gives the exact per-hectare factor: 0.40468564224. The calculator displays hectares to four decimal places (0.4047 ha for one acre) while the underlying multiplication uses the full factor. The inverse — dividing by 0.40468564224 — gives acres from hectares.

What a hectare actually measures

A hectare is a square 100 meters on each side: 100 m × 100 m = 10,000 m². It is the primary metric unit for land area in agriculture, land surveying, environmental science, and international real-estate comparisons. One hectare is approximately 2.471 acres. At the country scale, the USDA reports crop acreage in both acres and hectares to align with international agricultural statistics published by the FAO.

What an acre actually measures

An acre originated as the area a yoke of oxen could plow in a day: a strip one furlong long (660 ft) and one chain wide (66 ft). That origin explains why an acre is a long, narrow rectangle by definition rather than a square — a square plot of the same area has sides of about 208.7 ft (63.6 m). The modern international acre fixes the figure at exactly 4,046.8564224 m² regardless of shape, so a square lot, a rectangular parcel, or an irregular field of the same area all convert identically.

Acres, hectares, and square meters compared

One acre equals 0.4047 ha and 4,047 m². One hectare equals 2.471 acres and 10,000 m². For agricultural and large-tract land in the US, acreage is the everyday unit: USDA crop reports, ranch listings, and land surveys all express area in acres. For international comparisons, export-market specifications, or scientific publications, the same areas appear in hectares. The calculator shows all equivalents simultaneously, so a figure quoted in any one unit reads across to the others without a second lookup.

Worked examples

One acre is 0.4047 ha (4,047 m²; 43,560 ft²). A 2.5-acre parcel — a common size for a small rural lot — is 1.0117 ha (10,117 m²). Ten acres, a typical small farm tract, converts to 4.0469 ha. Each result follows directly from the single conversion factor, with no intermediate rounding step that would compound error.

Where this conversion is used in US practice

Real-estate listings in the US are quoted in acres for rural and large suburban parcels. When the same land is described in an international market, a scientific paper, or a USDA export report, the area appears in hectares. Zoning ordinances and subdivision plats in US municipalities are drafted in acres (or square feet for smaller lots), while environmental impact statements and wetlands-delineation reports — which follow federal and international scientific standards — typically use hectares. Surveyors and GIS analysts moving data between US and international datasets routinely convert between the two units.

Precision and rounding

The conversion factor is exact under the 1959 international definition of the yard and the SI definition of the meter. Results are therefore exact for the acreage entered, limited only by sensible display rounding. The calculator shows hectares to four decimal places, square meters to the nearest whole number, and square feet to the nearest whole number — each chosen to suit the scale of the unit. For survey-grade work, the area on a measured survey plat is more reliable than a converted marketing figure, because the input measurement, not the arithmetic, sets the real accuracy.

Using this alongside other BuildMetricLab tools

Once a land area is expressed in hectares or square meters it reads directly into area-based tools — concrete slab coverage, artificial turf quantities, or fence perimeter estimators. The acres-to-square-feet calculator handles the same input in US customary terms. All BuildMetricLab tools run entirely in your browser — no sign-up, no data sent anywhere, and every formula is shown on-page so the math can be audited.