Square Foot to Acre (ft² to ac)
Result
0.000022956841 Acre
Formula
ac = ft² × 0.000022956841
1 ft² = 0.000022956841 ac, and 1 ac = 43,560 ft².
Area factors are the square of the length factor: 1 ft = 0.3048 m, so 1 ft² = 0.3048² = 0.09290304 m². The acre is 43,560 ft² (4,046.8564224 m²) and the hectare 10,000 m².
Worked examples
- 1 ft² × 0.000022956841 = 0.000022956841 ac
- 10 ft² × 0.000022956841 = 0.00022956841 ac
- 100 ft² × 0.000022956841 = 0.0022956841 ac
Common mistakes
- Do not apply a length factor to an area: 100 m² is 1,076.39 ft², not 328 ft² (100 × 3.28).
- A plot described as "20 × 30 ft" is 600 ft²; convert each side to metres first or convert the area afterwards — never just one side.
Square Foot to Acre table
| Square Foot (ft²) | Acre (ac) |
|---|---|
| 1 | 0.000022956841 |
| 2 | 0.000045913682 |
| 5 | 0.00011478421 |
| 10 | 0.00022956841 |
| 20 | 0.00045913682 |
| 50 | 0.0011478421 |
| 100 | 0.0022956841 |
| 1,000 | 0.022956841 |
The units
- Square Foot (ft²)
- A square one foot on each side: exactly 0.09290304 m².
- Acre (ac)
- 43,560 square feet, exactly 4,046.8564224 m². 640 acres make a square mile.
Sources for these factors
- Handbook 44 (2024), Appendix C: General Tables of Units of Measurement — NIST
- Guide for the Use of the International System of Units (SP 811), Appendix B: conversion factors — NIST
Last reviewed against these sources. An automated check recomputes every factor from its definition on each build. How we check accuracy