Acres to Square Feet Converter
Convert acres to square feet for US land development and lot size measurement.
How It Works
Formula: acre to sq ft = value × 43560
Example: 1 acre = 43560 sq ft
Note: 1 acre equals 43,560 square feet, the standard US land and lot measurement.
Common Uses
Quick Conversion Table
| acre | sq ft |
|---|---|
| 10 | 435600 |
| 50 | 2178000 |
| 100 | 4356000 |
| 500 | 21780000 |
| 1000 | 43560000 |
| 2000 | 87120000 |
Rounding Rule
Rounded to whole square feet
Error Margin
±1 sq ft
Precision Guidance
For lots, round to whole sq ft. For surveys, keep exact values.
Common Mistakes
An acre is 43,560 sq ft, not 40,000. Use the exact figure for lot calculations.
Frequently Asked Questions
What is 1 acre in square feet?
1 acre equals 43,560 square feet, the standard US land measurement.
How do I convert acres to square feet?
Multiply the acre value by 43,560. For example, 0.5 acres × 43,560 = 21,780 sq ft.
How big is a 0.25 acre lot?
A quarter-acre lot equals 10,890 square feet, a common US suburban lot size.
Is an acre always 43,560 sq ft?
Yes, the US survey acre is defined as exactly 43,560 square feet.
Deep Dive Guide
Acres to Sqft: Exact Lot Size Conversion for US Real Estate
Convert acres to sqft accurately for US lot size measurement, land purchase decisions, and property boundary planning with the exact conversion factor.
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Exact Constants & Authoritative Sources
Every conversion on this page uses the fixed, internationally agreed constants below — drawn from NIST and the SI Brochure. No values are estimated or rounded as if exact. See the full list on our Sources & Standards page.
- EXACT1 acre = 4046.8564224 square metres (exact, 43,560 ft²)
- EXACT1 hectare (ha) = 10,000 square metres (definition)
- EXACT1 square foot (ft²) = 0.09290304 m² (exact)
- EXACT1 square mile = 2.589988110336 km² (exact)
Common Pitfalls & How to Avoid Them
Acre is not a square
An acre is 43,560 ft² of area in any shape — it can be long and thin. One acre = 4046.86 m² = 0.404686 hectare.
Section vs. hectare
A US "section" is 1 square mile = 259 ha. A hectare (10,000 m²) is ~2.47 acres. Keep the two apart when reading land listings.
A unit-conversion reference site has no manufacturer-specific or device calibration parameters, so "layered tuning" does not apply here. The only real error-handling is input validation: the converter rejects non-numeric, empty, or out-of-range entries and shows a clear message, then falls back to exact constants above. No estimated or rounded figures are ever presented as exact.
Authoritative sources for this page
- NIST (U.S. National Institute of Standards and Technology) — NIST SP 330 — The International System of Units (SI), 2019 edition
- BIPM (International Bureau of Weights and Measures) — SI Brochure — The International System of Units (9th edition)
Last Updated 2026 | This converter was reviewed for accuracy