Overview

An acre is an established unit of area originating in the English system and still used widely for land measurement in the United States and some Commonwealth countries. For the Brazilian state of the same name, see Acre (state). In everyday contexts an acre describes plots, farms, gardens and parcels of real estate.

Definition and common conversions

By international agreement the acre equals 4,046.8564224 square metres, which is equivalent to 4,840 square yards and 43,560 square feet. It is also close to 0.404686 hectares. Historically the acre was defined in terms of traditional English measures: one furlong by one chain. See the related terms furlong and chain for those linear units.

Characteristics and usage

The acre is primarily a land measure and remains common in legal documents, property descriptions and agricultural contexts in the United States and some former British territories. It is part of the broader family of English units (English) and is categorized as a unit of area (area). Many people relate an acre to familiar visual references, such as a typical American football field (including end zones) or the area that might be managed by a small farm.

Historical background

The word "acre" has medieval roots and originally described the area a single ox could plough in one day. Because that practical definition varied, medieval and later English monarchs enacted measures to fix its size: notable reforms involved kings such as Edward I, Edward III and later legislation. Over time the acre was standardized in law and remained in use as British units were carried overseas.

  • Exact international value: 4,046.8564224 m2 (based on the international foot).
  • Square yards: 4,840 (square yards).
  • Hectares: approximately 0.404686 (hectares).
  • Common usage persists in the United States and some Commonwealth countries, though many jurisdictions use metric units legally.

The acre is classed among traditional land units (unit) and remains a practical measure for real estate and agriculture. Its origin story, linking it to a farmer and oxen, explains why earlier definitions varied by region. For historical comparisons and modern references consult further resources on English measurement and land surveying practices (area, Acre (state), English units, football field).

For concise conversion tables and surveying notes see specialized references on chains and furlongs (chain, furlong) as well as legal definitions maintained by national standards bodies (unit, hectare, Commonwealth). Additional contextual information on historical legislation appears in records concerning monarchs who refined measurements (Edward I, Edward III).