Convert Square Feet to Acres - Area Converter
This converter transforms area values expressed in square feet into acres and vice versa using the fixed, established conversion factor. It is intended for planners, homeowners, land managers, and anyone who needs a fast, authoritative area conversion.
The tool uses the standard relationship applied in U.S. land measurement and surveying practice. For legal surveys or boundary determinations, always rely on certified survey data and local cadastral rules; this converter is best for calculations, estimates, and administrative tasks.
Interactive Converter
Convert between square foot and acre with precision rounding.
Quick reference table
| Square Foot | Acre |
|---|---|
| 1 ft² | 0 ac |
| 5 ft² | 0.0001 ac |
| 10 ft² | 0.0002 ac |
| 25 ft² | 0.0006 ac |
| 50 ft² | 0.0011 ac |
| 100 ft² | 0.0023 ac |
Methodology
The conversion is based on the internationally accepted definition that 1 acre equals 43,560 square feet. This factor is used directly—no approximation or intermediate unit conversions are required.
For conversions into metric units, the converter relies on the accepted equivalence 1 acre = 4,046.8564224 square metres when higher precision is required; that value is consistent with federal measurement references.
When presenting results, the tool follows common engineering practice for significant figures and allows users to round according to their reporting needs. For regulatory submissions, follow your agency's rules for rounding and accepted tolerances.
Expert Q&A
What is the exact conversion factor between square feet and acres?
One acre is defined as exactly 43,560 square feet. This is the standard factor used by federal and surveying authorities.
Is the acre an SI unit?
No. The acre is a non-SI customary unit of area commonly used in the United States and some other countries. For scientific work, use square metres (SI) or hectares; 1 acre = 4,046.8564224 square metres.
Can I use this converter for legal land surveys or property deeds?
This converter is suitable for calculations and estimates. For legal descriptions, boundary surveys, or deed preparation, rely on a licensed land surveyor and official cadastral records. Follow local jurisdiction rules for measurement tolerances and certified instruments.
How should I handle rounding and significant figures?
Choose rounding based on the use case: engineering designs typically keep 3–6 significant figures, while high-level planning may use 1–2. For regulatory filings, follow the specific agency or municipal rounding policy. When in doubt, preserve more digits and document the rounding method.
Why is the factor 43,560?
The value comes from historical land-measurement conventions in which an acre was standardized as a rectangle 660 feet by 66 feet, giving 43,560 square feet. Modern definitions use that exact numeric equivalence.
How do I convert very large or very small areas without losing precision?
Work in scientific notation or convert to a larger unit (acres or hectares) to avoid floating-point rounding. If you require sub-square-foot precision, use high-precision tools or software that support extended decimal places and reference authoritative unit definitions.
Sources & citations
- NIST Physical Measurement Laboratory — Weights and Measures — https://www.nist.gov/pml/weights-and-measures
- U.S. Geological Survey (USGS) — Land area and mapping resources — https://www.usgs.gov
- USDA Natural Resources Conservation Service (NRCS) — Unit conversion resources — https://www.nrcs.usda.gov
- MIT OpenCourseWare — Dimensional analysis and unit conversions — https://ocw.mit.edu