Hectares and acres — land units that decide crop yields
1 hectare = 2.471 acres. Convert wrong and a farm bid, a fertiliser order or a subsidy claim can be off by nearly 40%.
Farm auctions in Iowa quote acres. Farm auctions in France quote hectares. Farm auctions in Brazil quote alqueires (which vary by state). This unit chaos is not academic — it drives fertiliser purchases, crop insurance and land prices.
The exact factors
1 ac = 4,046.8564224 m² = 0.404686 ha (exact) > 1 ha = 10,000 m² = 2.471054 ac (exact) > 1 km² = 100 ha = 247.1 ac
Yield conversion is not one factor
Corn yield in the US is bushels per acre (bu/ac). Corn yield in Europe is tonnes per hectare (t/ha). Two factors apply at once — area and mass. A US corn bushel is 56 lb (25.4 kg). So 200 bu/ac × 25.4 kg/bu / 0.4047 ha/ac = 12,554 kg/ha = 12.55 t/ha. Multiply bu/ac by 0.0628 for a direct shortcut, but only for corn; wheat bushels are 60 lb.
Worked example — a 250-acre wheat farm
250 ac × 0.4047 = 101.2 ha. At a US wheat yield of 55 bu/ac × 60 lb = 3,300 lb/ac = 3.70 t/ac = 9.14 t/ha, the farm produces 250 × 3.70 = 925 short tons = 839 tonnes annually. Cross-check: 101.2 ha × 9.14 t/ha = 925 tonnes. Both routes agree when the bushel weight and area factor are handled cleanly.
Historic units that still appear
The alqueire varies from 2.42 ha (São Paulo) to 4.84 ha (Bahia). The Turkish dönüm is 0.1 ha. The Chinese mǔ (亩) is 666.7 m² = 0.0667 ha. Land contracts in these countries still quote local units alongside hectares — always confirm the regional definition before signing.
The five-second recap
Multiply acres by 0.4047 for hectares. For yield, multiply bu/ac by 0.0628 for corn (t/ha), by 0.0673 for wheat, by 0.0561 for soybeans. And check the local land unit if you are buying anywhere south of the Rio Grande.
Try the converters mentioned in this article
FAQ
How big is a football pitch in hectares?+
A regulation FIFA pitch (105 × 68 m) is 0.714 ha = 1.76 acres.
Why is the acre 4,046 m² and not a round number?+
The acre was defined as one furlong (660 ft) by one chain (66 ft) — a shape that could be ploughed by one ox team in a day. The metric conversion is unavoidably awkward.
Is the acre exact?+
Yes — 4,046.8564224 m² exactly since the international foot was defined as 0.3048 m in 1959.
This article was written by The Turbo Unit Converter engineering desk (Agricultural metrology) and last reviewed on 2026-06-28 against NIST SP 811 and the BIPM SI Brochure. Read our full editorial policy.