Area Conversion Calculator
Convert square metric and international-foot units, hectares, acres, and square miles with explicit land-unit definitions.
Content updated August 6, 2026
Acre and square-mile results use the international foot. Historical U.S. survey-foot land records need their stated legacy definition.
Convert one nonnegative area across ten square and land-area units, then compare the same input in every supported unit. Metric squares, international-foot squares, hectares, acres, and square miles remain clearly labeled.
Linear conversion factors must be squared for area. The engine converts through square metres using exact SI prefixes and the exact international foot, rather than applying a length factor only once.
The Area Conversion formula
Converted area = entered area × square metres per source unit ÷ square metres per destination unitSquare-unit factors are the corresponding exact length factors squared; acre and square mile use the international foot.
Worked example
One international-foot acre multiplied by exactly 4,046.8564224 square metres per acre equals 4,046.8564224 square metres.
Assumptions, rounding, and limitations
Assumptions
- The input is a nonnegative scalar area, not a set of dimensions.
- Square inch, foot, yard, and mile use international-foot definitions.
- Acre means 43,560 international square feet.
- Hectare means exactly 10,000 square metres.
Rounding: The engine does not intentionally round intermediate results. Displays use up to 12 significant digits and scientific notation for very large or small values.
Limitations
- Does not include historical U.S. survey-foot acres or square miles, local land units, map projections, coordinate reference systems, or curved-surface geodesic area.
- Converts an already measured area; it does not calculate area from boundaries, dimensions, slopes, or irregular geometry.
Sources
- U.S. Survey Foot: Revised Unit Conversion Factors — National Institute of Standards and Technology
- NIST Guide to the SI, Appendix B: Conversion Factors — National Institute of Standards and Technology
Area factors are squared length factors
Because one international foot is exactly 0.3048 metre, one square foot is exactly 0.3048², or 0.09290304, square metre. The same rule makes one square international mile exactly 2,589,988.110336 square metres.
A hectare is exactly 10,000 square metres. An international-foot acre is 43,560 square feet, which is exactly 4,046.8564224 square metres.
Survey-foot land records need their stated definition
NIST lists different metric equivalents for international-foot and historical U.S. survey-foot acres. This calculator uses the international-foot acre and square mile adopted for current federal conversion tables.
Do not silently apply these factors to a legacy plat, coordinate system, or land record that explicitly uses survey feet. Preserve the unit basis stated by the source record.
Frequently asked questions
▶How many square metres are in one acre?
One international-foot acre is exactly 4,046.8564224 square metres.
▶How many acres are in one square mile?
One international square mile contains exactly 640 international-foot acres.
▶How many square feet are in one square metre?
One square metre is approximately 10.7639104167 square feet; the engine retains the exact underlying square-foot factor before display formatting.
▶Is a hectare the same as an acre?
No. A hectare is exactly 10,000 square metres and is approximately 2.47105381467 international-foot acres.
▶Does this support U.S. survey-foot acres?
No. Acre and square-mile choices use the international foot. Legacy survey-foot data needs its explicitly documented historical conversion.
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Open calculator →Disclaimer: Area Conversion Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.