Acres vs Hectares: The Key Differences and How to Convert

6 min read•June 9, 2026•Reviewed: June 9, 2026

✓Reviewed by Apex Conversion Editorial Team · Last reviewed June 9, 2026

Land area is one of the last domains where two measurement systems still operate side by side at full scale. The acre dominates land transactions, farming, and zoning in the United States; the hectare is the standard everywhere else and in all international agricultural statistics. Anyone reading a foreign property listing, an FAO crop report, or a land deed from another country needs to move between them.

The conversion is a single fixed factor: 1 hectare = 2.47105 acres, and 1 acre = 0.404686 hectares. The mental shortcut — a hectare is about two and a half acres — is accurate to within 1.2% and good enough for most practical comparisons.

What Is an Acre?

The acre originated in medieval England as the area a yoke of oxen could plough in one day — standardized as one chain by one furlong (66 × 660 feet), which equals 43,560 square feet or about 4,047 m². It survives in the US Public Land Survey System, where land is divided into square-mile sections of 640 acres, quarter sections of 160 acres, and so on — which is why so many American farm sizes are multiples of 40.

Today the acre is the standard unit for US real estate, agriculture, and forestry, and remains in informal use in the UK. A typical US suburban lot is 0.2–0.5 acres; the median US farm is around 80 acres.

What Is a Hectare?

The hectare is the metric land unit: a square 100 meters on each side, equal to exactly 10,000 m². It is not formally an SI unit but is accepted for use with SI, and it is the standard land measurement in nearly every country outside the US. The name combines 'hect-' (hundred) with 'are', a historical unit of 100 m².

The hectare's strength is decimal coherence: 100 hectares make exactly one square kilometer, so national land statistics, satellite-derived land cover data, and agricultural yield figures (tonnes per hectare) chain together without conversion factors.

Acre and Hectare Conversion Formulas

ac → ha:  ha = ac × 0.404686
ha → ac:  ac = ha × 2.47105

Quick estimates:
  ha × 2.5 ≈ ac  (within 1.2%)
  ac × 0.4 ≈ ha  (within 1.2%)

Land reference:
    1 ac  = 0.405 ha = 43,560 ft²
   40 ac  = 16.2 ha   (US 'forty')
  160 ac  = 64.7 ha   (quarter section)
  640 ac  = 259 ha    (1 square mile)
  100 ha  = 247 ac    (1 km²)

Frequently Asked Questions

Which is bigger, an acre or a hectare?

A hectare is much bigger — about 2.47 acres. A hectare is a 100 m × 100 m square; an acre is roughly 64 m × 64 m if squared up.

How many acres are in a square mile?

Exactly 640 acres. The US Public Land Survey divides land into square-mile sections of 640 acres, which is why 40-, 80-, and 160-acre parcels are so common.

Why do international crop reports use hectares?

The hectare is the metric standard adopted by the FAO and nearly all national statistics agencies. Yields are quoted in tonnes per hectare; converting to US bushels per acre requires both an area and a quantity conversion.

Is the UK acre the same as the US acre?

Effectively yes. Both descend from the same imperial definition; the microscopic difference between the international and US survey foot definitions amounts to a few square feet per acre and is irrelevant in practice.

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