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Exact factorsSI ↔ ImperialFree

Area Unit
Converter

Convert any area between square metres, square feet, square yards, acres, hectares, square kilometres and square miles. Uses exact NIST conversion factors — enter one value, see all units at once.

Who it's for: Architects, planners, and owners who need to switch quickly between metric and imperial area units during design development or bidding — no conversion factor lookup needed.

Reference
1 ft² = 0.09290304 m² · 1 acre = 4,046.856 m² = 43,560 ft² · 1 hectare = 10,000 m² = 2.471 acres · 1 mi² = 2.59 km².
Convert area
All units at once

How to use this calculator

1
Enter the area value
Type the number you want to convert. The input accepts any positive whole or decimal number.
2
Choose the source unit
Pick the unit your value is already in: square metres, feet, yards, acres, hectares, square kilometres, miles, centimetres, or inches.
3
Click Convert
Hit the Convert button to run the calculation.
4
Read every converted unit at once
All nine units appear in a single table — take the row you need. Very large or very small values switch automatically to exponential notation.

The formula

Every area unit converts to any other by first expressing it in square metres, then dividing by the target unit's factor.

Result = (Input × from-unit factor) ÷ to-unit factor

Conversion factors (NIST exact):
1 ft² = 0.09290304 m² · 1 yd² = 0.83612736 m²
1 acre = 4,046.856 m² · 1 ha = 10,000 m²
1 km² = 1,000,000 m² · 1 mi² = 2,589,988 m²

Worked example

Example
Enter 1 acre and click Convert. The calculator multiplies by 4,046.856 to get 4,046.86 m². Dividing by each other unit's factor produces 43,560 ft², 4,840 yd², 0.4047 ha, 0.004047 km², 0.001563 mi², and 6,272,640 in² — all in one step.

When this estimate will be off

  • The factors are mathematically exact by NIST definition; displayed precision is capped at six decimal places for readability.
  • This converter handles flat two-dimensional area only — sloped roofs, curved surfaces, or hillside sites need their actual surface area computed first.
  • Acres shown are the international acre (43,560 ft²). The US survey acre differs by less than 0.002%; both are identical for practical planning work.
  • Very large results appear in exponential notation (e.g. cm²) — the value is exact, but copy with care when transcribing to another system.

Frequently asked questions

A common mistake: The factors are mathematically exact by NIST definition; displayed precision is capped at six decimal places for readability.

Exactly 43,560 ft². One acre equals 43,560 square feet by NIST definition, which works out to 4,046.856 m² or 0.4047 hectares. The acre remains the standard land-area unit in US real estate and zoning; most other countries use hectares.

A hectare is 10,000 m² — the metric standard for land area. An acre is 4,046.856 m². One hectare equals approximately 2.471 acres. Hectares appear in European and international planning documents; acres are common in US, UK, and Commonwealth land transactions.

Multiply by 0.09290304 — the exact NIST factor (derived from 1 ft = 0.3048 m). For example, 1,000 ft² × 0.09290304 = 92.90 m². This calculator applies that factor automatically for every ft² conversion.

The display switches to scientific notation for values above 10 million or below 0.0001. For example, 1 acre in square centimetres is about 4.047 × 10⁷ cm² — cleaner than writing 40,468,564. The underlying figure is mathematically exact.

Sources

  • NIST SP 811 (2008), Appendix B — exact SI and US customary conversion factors: 1 ft² = 0.09290304 m² (exact), 1 acre = 4046.8564224 m² (exact), 1 ha = 10 000 m² (exact)

This free Area Unit Converter is built and maintained by DataDrivenAEC, using the relevant codes and standards. It does not substitute for professional judgment.