Square Feet to Acres Converter — Convert ft² to acres (Exact: 1 acre = 43,560 ft²)
Accurate square feet (ft²) to acres converter using the exact U.S. land survey definition: 1 acre = 43,560 square feet. Ideal for real estate listings, parcels, plats, farm fields, zoning, and site plans. Includes precise formulas, worked examples, expanded reference tables, rounding guidance, detailed FAQs, and practical tips.
Exact factor: 1 acre = 43,560 ft² ⇒ acres = ft² ÷ 43,560. See all free area metric converters.
About Square Feet to Acres Conversion
The square foot (ft²) dominates residential listings, room schedules, and interior takeoffs in the U.S., while acres (ac) summarize land parcels, lots, farms, and campus footprints. Converting ft² to acres helps you reconcile floor-area-centric data with parcel-level reporting, valuations, and zoning summaries.
Because 1 acre is defined exactly as 43,560 ft², the conversion is straightforward and exact. Keep one canonical unit in storage (many teams choose ft² for buildings and acres for land), compute in that unit, and convert for presentation. Round once on output so your PDFs, spreadsheets, and dashboards always match.
A practical workflow is to store area_ft2 and derive acres on the fly for listings, assessor extracts, and marketing sheets, or to store area_acres for parcel systems and derive square feet for construction and site-planning documents. Either approach works as long as you are consistent and document your constants.
Square Feet to Acres Formula
Exact relationship
Use either expression:
acres = ft² ÷ 43,560
// inverse
ft² = acres × 43,560Example:
18,200 ft² ÷ 43,560 = 0.41798 acresRelated Area Converters
What is a Square Foot (ft²)?
A square foot is the area of a square one foot on a side. It is ubiquitous in U.S. residential real estate, interior design, flooring, and tenant improvements. For exterior site work and parcels, square feet often appear alongside acres to give both a precise and a high-level view of size.
What is an Acre (ac)?
An acre is a land area unit equal to exactly 43,560 ft². It originated from surveying practice based on chains and furlongs, but today the definition is fixed and universal in U.S. land records. Many zoning codes, appraisal models, and agricultural references communicate parcel size primarily in acres.
Step-by-Step: Converting ft² to acres
- Read the area in square feet (ft²) from your plan, listing, or GIS attribute.
- Divide by 43,560 to get acres (ac).
- Round once at presentation (e.g., 2–4 decimals for listings; more for engineering if justified).
Example walkthrough:
Input: 65,340 ft²
Compute: 65,340 ÷ 43,560 = 1.499... ac
Output: 1.500 acres (UI, 3 decimals)Common Conversions
Everyday quick checks (ft² → acres)
| ft² | acres | ft² | acres |
|---|---|---|---|
| 5,000 | 0.114784 | 10,000 | 0.229568 |
| 21,780 (½ ac) | 0.500000 | 43,560 (1 ac) | 1.000000 |
| 65,340 (1½ ac) | 1.500000 | 87,120 (2 ac) | 2.000000 |
| 108,900 (2½ ac) | 2.500000 | 217,800 (5 ac) | 5.000000 |
| 435,600 (10 ac) | 10.000000 | 871,200 (20 ac) | 20.000000 |
Quick Reference Table
Acres to square feet (ac → ft²)
| acres | ft² | acres | ft² |
|---|---|---|---|
| 0.10 | 4,356 | 0.25 | 10,890 |
| 0.50 | 21,780 | 0.75 | 32,670 |
| 1.00 | 43,560 | 2.00 | 87,120 |
| 5.00 | 217,800 | 10.00 | 435,600 |
| 20.00 | 871,200 | 40.00 | 1,742,400 |
Precision, Rounding & Significant Figures
Operational rounding
For MLS listings and brochures, 2–4 decimals in acres usually balance readability and accuracy (e.g., 0.23 ac). For engineering, subdivision, or plat review, match your survey accuracy and round once at presentation. Keeping internal values exact ensures consistency across PDFs, emails, and CSV exports.
Consistent documentation
Publish a one-page methods note with constants and rounding policy. Example: “Exact: 1 acre = 43,560 ft²; round once at presentation; field names: area_ft2, area_acres.” Consistency prevents confusion when brokers, surveyors, engineers, and assessors collaborate on the same data.
Where This Converter Is Used
- 🏠 Real estate & MLS: Listing lot sizes in acres while floor areas remain in ft².
- 📐 Survey & plats: Parcel and subdivision summaries that must match recorded acreage.
- 🌾 Agriculture: Field and pasture acreage with ft² detail for infrastructure pads.
- 🏛️ Planning & zoning: Minimum lot sizes and density metrics aligned to acres.
- 🏗️ Site & civil: Converting detailed takeoffs (ft²) into parcel-level summaries (acres).
Frequently Asked Questions
What is the exact formula to convert square feet to acres?
Use the fixed definition: 1 acre = 43,560 ft². Therefore acres = ft² ÷ 43,560. The inverse is ft² = acres × 43,560. These are exact relationships used in deeds, plats, assessor systems, and appraisal reports, so your numbers will match official records when applied consistently.
Where does the 43,560 ft² per acre figure come from?
Historically, an acre was standardized as 10 square chains; one chain is 66 ft, so a square chain is 66 × 66 = 4,356 ft². Ten of those make 43,560 ft² per acre. Modern U.S. property work retains this exact definition for parcels, tax lots, and recorded plats.
Do I need to worry about the U.S. survey foot vs. the international foot?
Not for this converter. The acre definition of 43,560 ft² is the same either way, and the 2023 U.S. retirement of the survey foot moved most practice to the international foot (0.3048 m exactly). If you compute in meters first, just be clear about CRS and area measurement method.
How should I round ft² ↔ acres in quotes, listings, and reports?
Calculate with full precision internally and round once at presentation. Listings commonly show acres to 2–4 decimals (e.g., 0.25 ac or 3.1275 ac). Appraisals and engineering sheets may keep more decimals depending on survey accuracy. Document the policy so PDFs, exports, and dashboards always agree.
Can I add square feet and acres in the same spreadsheet column?
Avoid mixing units within one numeric field. Normalize areas to a canonical unit—many teams pick square feet or acres—perform math there, and convert for display. Mixed-unit storage is a common cause of audit discrepancies and off-by-percent errors.
Does GIS projection affect square feet to acres conversion?
The unit conversion factor is exact and independent of projection. Projection (or geodesic methods) only affects how you measure the polygon area. Once the area is computed in ft² or m², converting to acres uses the same fixed constants everywhere.
What precision should I store in my database?
Store full precision in a single canonical field such as area_ft2 or area_acres (or area_m2 for SI). Convert on read for UI and reports, and round once at output. This prevents drift from double-rounding across services, exports, and BI tools.
How can I sanity-check my conversions quickly?
Memorize a few anchors: 1 acre = 43,560 ft²; 0.5 acre = 21,780 ft²; 2 acres = 87,120 ft². Conversely, 10,890 ft² = 0.25 ac; 5,000 ft² ≈ 0.1148 ac. Use these as quick regressions to confirm both directions.
Is an acre the same as a survey acre, and what about hectares?
In U.S. practice, 'acre' refers to the exact 43,560 ft². Hectares are metric land units used internationally: 1 hectare = 10,000 m² ≈ 2.47105381 acres. Keep acres for U.S. land work and convert to hectares for international comparisons.
What field names and documentation reduce confusion between teams?
Use explicit, unit-suffixed names like area_ft2, area_acres, and area_m2. Add a short methods note: “Exact constants: 1 acre = 43,560 ft²; round once at presentation.” Consistent naming and documented constants keep partners and vendors aligned.
Tips for Working with ft² & acres
- Keep ft² or acres canonical in storage, not both; convert on read for UI.
- Round once at presentation, and apply the same rule across PDFs, exports, and dashboards.
- Use explicit field names (area_ft2, area_acres) and include constants in your methods note.
- Validate with a regression set (e.g., 21,780 ft² ↔ 0.5 ac, 43,560 ft² ↔ 1.0 ac) in both directions.