Square Foot to Acre Conversion Calculator: Free Online Tool
Convert square feet to acres with our free online area converter.
Square Foot to Acre Calculator
How to Use the Calculator:
- Enter the value you want to convert in the 'From' field (Square Foot).
- The converted value in Acre will appear automatically in the 'To' field.
- Use the dropdown menus to select different units within the Area category.
- Click the swap button (⇌) to reverse the conversion direction.
How to Convert Square Foot to Acre
Converting Square Foot to Acre involves multiplying the value by a specific conversion factor, as shown in the formula below.
Formula:
1 Square Foot = 0.0000229568 acresExample Calculation:
Convert 10 square feet: 10 × 0.0000229568 = 0.000229568 acres
Disclaimer: For Reference Only
These conversion results are provided for informational purposes only. While we strive for accuracy, we make no guarantees regarding the precision of these results, especially for conversions involving extremely large or small numbers which may be subject to the inherent limitations of standard computer floating-point arithmetic.
Not for professional use. Results should be verified before use in any critical application. View our Terms of Service for more information.
What is a Square Foot and a Acre?
The square foot (plural: square feet; symbol: ft², sq ft, or SF) is an imperial and US customary unit of area. It is defined as the area of a square with sides measuring exactly one foot (0.3048 meters) in length.
One square foot is equal to:
- 144 square inches (in²)
- 1/9 of a square yard (yd²)
- 0.09290304 square meters (m²) (exactly, based on the international foot definition)
- 929.0304 square centimeters (cm²)
It is widely used for measuring room dimensions, house sizes, and smaller land areas in countries using the imperial or US customary systems.
The acre (symbol: ac) is a unit of land area used in the imperial and US customary systems. It is traditionally defined as the area of one chain by one furlong (66 by 660 feet). This is exactly equal to:
- 10 square chains
- 1/640 of a square mile
- 4,840 square yards
- 43,560 square feet
- Approximately 4,046.856 square meters (m²)
- Approximately 0.4047 hectares (ha)
While derived from traditional farming practices, its size is now legally defined based on the international yard.
Note: The Square Foot is part of the imperial/US customary system, primarily used in the US, UK, and Canada for everyday measurements. The Acre belongs to the imperial/US customary system.
History of the Square Foot and Acre
- Roots in the Foot: The square foot naturally derives from the foot, a unit of length used since antiquity. The length of the foot varied significantly across different cultures and historical periods, often based on anatomical averages or royal decrees.
- English Standardization: In England, the foot (and thus the square foot) underwent various standardizations. Its use became deeply ingrained in land surveying, architecture, and trade.
- International Foot (1959): To resolve slight discrepancies between the US customary foot and the imperial foot, the "international yard and pound agreement" of 1959 defined the international yard as exactly 0.9144 meters. This implicitly defined the international foot as exactly 0.3048 meters. Consequently, the international square foot is exactly 0.09290304 square meters.
- Persistence: Despite widespread global metrication, the square foot remains the standard unit for many applications, particularly in real estate and construction, in the United States, Canada, the United Kingdom, India, Pakistan, Bangladesh, Malaysia, Singapore, Hong Kong, and several other nations influenced by British or American standards.
- Origin: The word "acre" derives from the Old English word æcer (originally meaning "open field"), cognate with German Acker and Latin ager. It traditionally represented the amount of land that could be ploughed by one man with one yoke of oxen in one day. This practical definition naturally led to considerable variation in its size depending on the land quality and local customs.
- Medieval Variations: Throughout the Middle Ages in England, the acre's size varied. Different regions used "customary acres" based on local practices, often related to the quality of the land or the length of a standard furrow (furlong).
- Standardization (Gunter's Chain): The standardization of the acre is closely linked to the invention of Gunter's chain in 1620. This measuring chain, 66 feet long (divided into 100 links), became a standard survey tool. The traditional definition of an acre as a strip of land one furlong (10 chains or 660 feet) long and one chain (66 feet) wide was easily measured using the chain. This area is precisely 10 square chains.
- Statutory Acre: In England and Wales, the Weights and Measures Act of 1878 formalized the "statutory acre" based on the imperial yard, solidifying the definition as 4,840 square yards (or 43,560 square feet). This is the acre commonly used today in the UK, US, and Commonwealth countries.
- Metrication: Although many countries using the acre have largely adopted the metric system for other measurements, the acre persists strongly in land transactions and agriculture due to historical precedent and cultural familiarity. The hectare (10,000 m²) is the more common metric unit for land.
Common Uses for square feet and acres
Explore the typical applications for both Square Foot (imperial/US) and Acre (imperial/US) to understand their common contexts.
Common Uses for square feet
The square foot is a ubiquitous unit of area in specific sectors and regions:
- Real Estate (US, Canada, UK, etc.): The primary unit for specifying the area of residential homes, apartments, office spaces, and commercial properties in listings, appraisals, and architectural drawings.
- Construction & Architecture: Used universally in these regions for floor plans, material estimation (flooring, drywall, roofing), and building design.
- Home Improvement: Standard measurement for purchasing materials like tiles, carpet, paint coverage, and wallpaper.
- HVAC Calculations: Used to determine heating and cooling requirements based on room or building area.
- Gardening & Landscaping: Measuring smaller plots, garden beds, patios, or deck areas.
- Rental Space: Often used for pricing storage units or exhibition spaces.
- Art & Signage: Describing the area of canvases, prints, or signs.
Common Uses for acres
The acre remains a primary unit for land measurement in several countries, particularly within specific sectors:
- Real Estate (US, UK, Commonwealth): Standard unit for describing the size of land parcels in property listings, deeds, and surveys, especially for residential lots larger than typical city plots, rural properties, and undeveloped land.
- Agriculture: Widely used by farmers to measure field sizes, calculate crop yields, allocate resources (like fertilizer or seeds), and comply with agricultural regulations.
- Land Management and Planning: Used in zoning regulations, environmental assessments, and land development projects to specify area requirements or limitations.
- Historical Documents: Understanding the acre is crucial for interpreting historical land records, surveys, and deeds.
- Informal Comparisons: Often used informally to help visualize the size of large areas, even where metric units are officially standard.
Frequently Asked Questions
Questions About Square Foot (ft²)
How big is a square foot visually?
One square foot is the area of a square measuring 1 foot (12 inches or 30.48 cm) on each side. For comparison:
- It's the typical size of a large ceramic floor tile (12"x12").
- It's slightly larger than a standard sheet of US letter paper (8.5"x11" = 93.5 in²).
- A large hardcover notebook might be close to this area.
How many square inches (in²) are in a square foot (ft²)?
There are exactly 144 square inches (in²) in one square foot (ft²). This is because 1 foot = 12 inches, so 1 ft² = (12 inches) × (12 inches) = 144 in².
How many square feet (ft²) are in a square yard (yd²)?
There are exactly 9 square feet (ft²) in one square yard (yd²). This is because 1 yard = 3 feet, so 1 yd² = (3 feet) × (3 feet) = 9 ft².
How do you convert square feet (ft²) to square meters (m²)?
To convert square feet to square meters, multiply the area in square feet by 0.09290304. For a quick approximation, you can divide the number of square feet by 10.764. For example, 100 ft² is exactly 9.290304 m².
How many square feet (ft²) are in an acre (ac)?
There are exactly 43,560 square feet (ft²) in one acre (ac).
Is the square foot (ft²) an SI unit?
No, the square foot is not part of the International System of Units (SI). It is a unit within the imperial system and US customary units. The corresponding SI unit for area is the square meter (m²).
About Acre (acre)
How big is an acre visually?
An acre is 43,560 square feet. While it can be any shape, a square acre would be about 208.71 feet on each side. A common visual comparison is an American football field: one acre is about 90.75% of the total area of a standard American football field (which is 120 yards long by 53.33 yards wide, or 57,600 sq ft including end zones). Excluding the end zones (100 yards by 53.33 yards, or 48,000 sq ft), an acre is about 90.75% of the playing field area.
How many square feet are in an acre?
There are exactly 43,560 square feet in one acre. This definition (1 furlong × 1 chain = 660 ft × 66 ft) is precise.
How many square yards are in an acre?
There are exactly 4,840 square yards in one acre (since 1 yard = 3 feet, 1 square yard = 9 square feet; 43,560 / 9 = 4,840).
How many acres are in a square mile?
There are exactly 640 acres in one square mile.
How many acres are in a hectare?
One hectare is equal to 10,000 square meters. Since one acre is approximately 4,046.856 square meters, one hectare contains approximately 2.471 acres (10,000 / 4046.856 ≈ 2.471). Conversely, one acre is approximately 0.4047 hectares.
Is the acre an SI unit?
No, the acre is not part of the International System of Units (SI). It belongs to the imperial and US customary systems. The SI unit for area is the square meter (m²). For land measurement, the hectare (ha), equal to 10,000 m², is commonly used in metric contexts and is accepted for use with SI.
Conversion Table: Square Foot to Acre
| Square Foot (ft²) | Acre (acre) |
|---|---|
| 1 | 0 |
| 5 | 0 |
| 10 | 0 |
| 25 | 0.001 |
| 50 | 0.001 |
| 100 | 0.002 |
| 500 | 0.012 |
| 1,000 | 0.023 |