How to use this acreage calculator
Enter a land area and pick the unit it's currently measured in — acres, hectares, square feet, square meters, square yards, or square miles. The calculator converts that value to acres, hectares, square feet, and square meters at once, so you can immediately see the same parcel expressed in whichever unit a deed, listing, survey, or zoning document uses.
What an acre actually is
An acre is a unit of land area with roots in medieval English agriculture, originally the amount of land a yoke of oxen could plow in one day. It was later standardized as exactly 43,560 square feet, or equivalently 4,840 square yards, or one chain by one furlong (66 ft × 660 ft). Since the international foot was fixed at exactly 0.3048 meters in 1959, one acre now equals exactly 4,046.8564224 square meters. That is the precise conversion factor this calculator uses — nothing is rounded or approximated.
The core conversion factors
All conversions on this page reduce to a single common unit, square meters, then convert back out. The key relationships are: 1 acre = 43,560 sq ft = 4,840 sq yd = 4,046.8564224 sq m = 0.40468564224 hectares. Going the other direction, 1 hectare (a 100 m × 100 m square) equals 2.47105381467 acres, and 1 square mile (640 acres) equals 258.9988110336 hectares. Because a hectare is exactly 10,000 sq m, and an acre is exactly 4,046.8564224 sq m, the acre-to-hectare ratio is fixed and never changes with location or survey method.
Common reference points
A useful mental benchmark: a standard American football field, including both end zones, is close to 1.32 acres (about 57,600 sq ft), and just the playing field between end lines is about 1.1 acres. A regulation soccer pitch is roughly 1.6 to 1.9 acres depending on size. A typical suburban US residential lot is often around a quarter acre (0.25 acre ≈ 10,890 sq ft). One square mile equals exactly 640 acres, which is why "a section" in the US Public Land Survey System (one square mile) is such a common land-division unit in rural real estate and farming.
Why the exact figure matters
Land transactions, property tax assessments, and agricultural planning (seed, fertilizer, and irrigation rates are often quoted per acre or per hectare) are sensitive to rounding errors, especially on large parcels. Using an approximate factor like "1 acre ≈ 4,047 sq m" instead of the exact 4,046.8564224 sq m introduces a discrepancy of about 0.0035% per acre — negligible for a small residential lot, but it can shift the reported area of a multi-hundred-acre farm or ranch by a meaningful fraction of an acre. This calculator always uses the exact defined value.
Frequently asked questions
How many square feet are in an acre? Exactly 43,560 square feet.
How many acres are in a hectare? One hectare equals about 2.4710538 acres.
How many acres are in a square mile? Exactly 640 acres — this is the basis of the "section" unit used in US land surveying.
Is an acre the same everywhere in the world? The international acre used here (4,046.8564224 sq m) is the modern legal standard in the US, UK, Canada, and most Commonwealth countries. A separate "US survey acre," based on the pre-1959 survey foot, differs from the international acre by only about 2 parts per million — a difference of roughly 0.16 sq m per acre — and is being phased out of official US use by the National Geodetic Survey.
What's a quick way to estimate acres from feet? Multiply length by width in feet to get square feet, then divide by 43,560. For example, a 200 ft × 435.6 ft rectangular lot is 87,120 sq ft, or exactly 2 acres.
Worked example
Suppose a real estate listing states a lot is 2.5 acres and you want to confirm the size in square meters for an international buyer. Multiply 2.5 by 4,046.8564224 to get 10,117.141056 square meters, or divide by 10,000 to get 1.01171410... hectares. Enter 2.5 with unit "Acres" above to see this computed automatically alongside the square-foot and square-yard equivalents.