Article — Acres to Hectares Converter
Acres to Hectares: How the Land Area Conversion Works
One hectare equals 2.47105 acres, and one acre equals 0.404686 hectares. The relationship is exact: 1 hectare is defined as 10,000 square meters and 1 acre as 4046.8564224 square meters. Multiply or divide and you are done.
The conversion sits at the intersection of two measurement traditions. The acre descends from medieval English land surveying, where it represented the area a team of oxen could plow in a day. The hectare arrived with the French metric system in 1795 as a clean decimal unit (one hundred ares, where an are is 100 square meters). The factor between them has been stable since the 1959 international yard and pound treaty fixed the foot at exactly 0.3048 m.
What is acres to hectares conversion?
The conversion translates a land area expressed in acres into hectares, or vice versa. Because both units have exact metric definitions, the result is not a measurement; it is arithmetic. The international acre equals 4046.8564224 m squared. The hectare equals 10,000 m squared. Dividing one by the other gives the conversion factor to as many decimals as you want.
This calculator uses 2.47105 acres per hectare and 0.404686 hectares per acre, which is accurate to six significant figures. For survey-grade work, NIST recommends 0.40468564224 ha per acre, which carries the full exact value.
Until 2023, the US technically maintained two acres: the international acre (4046.8564 m squared) and the US survey acre (4046.8726 m squared). NIST retired the survey foot in 2023, which collapsed the two definitions into one for all new land records.
The acres to hectares formula
The forward formula multiplies acres by 0.404686 to get hectares. The reverse multiplies hectares by 2.47105 to get acres. For mental math, treat 1 acre as 0.4 ha and 1 ha as 2.5 ac, then nudge the answer by about one percent in the appropriate direction.
ha = acres × 0.404686 acres = ha × 2.471051 ha = 10,000 m² 1 ac = 4046.8564 m²1 km² = 100 ha 1 mile² = 640 ac = 259 haAcres and hectares in real estate
Real estate deeds in the United States, the United Kingdom, and parts of the Commonwealth describe lots in acres or fractions thereof. A typical American suburban lot is one-quarter to one-third of an acre (1000 to 1350 m squared, or 0.1 to 0.135 ha). A rural homestead might span 10 to 40 acres (4 to 16 ha). Anything over 100 acres usually changes hands as a working farm or ranch rather than a residential property.
European listings show hectares for anything larger than a building lot. A French chateau estate might list as 5 hectares (12.4 acres), a Tuscan olive grove as 3 hectares (7.4 acres), and a Polish family farm as 20 hectares (49.4 acres). Within a single city, residential lots are usually quoted in square meters: a Warsaw apartment plot of 800 m squared equals 0.08 ha or 0.198 acres.
- 0.1 ha = 0.247 acres (standard urban lot)
- 0.5 ha = 1.236 acres (large residential parcel)
- 2 ha = 4.94 acres (small holding)
- 10 ha = 24.71 acres (family farm)
- 40 ha = 98.84 acres. 160 acres = a quarter section (64.75 ha)
- 100 ha = 247.1 acres (one square kilometer)
- 259 ha = 640 acres (one square mile = section)
Acres vs hectares in farming
US agricultural statistics, subsidy payments, and yield records all run in acres. A typical Iowa corn farm produces 180 bushels per acre. The USDA reports planted acreage and harvested acreage in millions of acres per crop. The Farm Bill pays Conservation Reserve Program participants per acre per year.
The EU mirrors the same system in hectares. CAP direct payments are calculated per hectare. European yield benchmarks are tonnes per hectare. A French wheat farm might average 7 tonnes per hectare, which translates to 104 bushels per acre at standard 60 lb test weight. Converting between USDA and Eurostat data requires the 2.47105 factor every time, which is why this conversion appears in nearly every cross-border agricultural report.
History of the acre and hectare
The acre is one of the oldest English measurements still in routine use. Its first written legal definition appears in the Composition of Yards and Perches, an English statute of around 1300 that fixed the acre at 4 perches wide by 40 perches long. A perch (also called a rod) was 16.5 feet, so the acre measured 66 by 660 feet, or 43,560 square feet. That definition has not changed in more than 700 years.
The hectare appeared during the French Revolution. The metric system, drafted between 1791 and 1795, introduced the are as a square dekameter (100 square meters) and the hectare as 100 ares. The unit was officially adopted across French territory in 1801 and spread through Napoleon's conquests. By 1875, when the Metre Convention was signed in Paris, the hectare was the dominant unit of agricultural area in continental Europe.
Acres to hectares around the world
About 95 percent of the world's countries use hectares. The exceptions are the United States, Myanmar, and a handful of Pacific island nations. The United Kingdom retains acres in agricultural and Crown Estate records but uses hectares in all government statistics. India officially uses hectares but keeps bigha, gunta, and other regional units in rural land transactions. Australia and Canada moved to hectares for government reporting in the 1970s.
The Irish acre (6555 m squared), Scottish acre (5081 m squared), and Cheshire acre (4047 by 2 = 8094 m squared) all differ from the international acre. They appear in historical deeds and occasionally in present-day rural Ireland and Scotland. Always confirm which acre a document refers to before converting.
Common acres to hectares mistakes
For cross-checks, remember that 1 hectare is approximately the size of an international rugby pitch, and 1 acre is roughly the size of an American football field excluding the end zones. If your answer pictures something wildly different, recheck the math.
The most frequent error is treating acres and hectares as roughly equal. They differ by a factor of 2.5, which is more than two and a half times. A 40-acre property is not 40 hectares; it is 16.19 hectares. Another common slip is using 2.5 as an exact conversion rather than 2.47105; over 1000 hectares, the rounding error grows to 28 acres. For real estate or tax work, always use at least four decimals in the factor.
Surveyors face a more subtle issue: deeds drafted before 2023 in the US used the survey foot, which made the acre 4046.873 m squared rather than 4046.8564 m squared. The 17-parts-per-million difference is negligible for a one-acre lot (0.07 square meters) but matters for a 10-section ranch (700 square meters off). When importing older PLSS data into a GIS, check whether the source feet are survey or international and apply the right acre constant.