Square Feet to Acres
Divide square feet by 43,560. Enter the lot width and depth in feet to convert.
Indicative estimate · not a survey or a design · see methodology
Real lots are rarely rectangles. Draw your plot on the satellite map and get the exact area, slope and orientation.
Draw my landAcre conversions and common lot sizes
| Area | Square feet | m² | What it looks like |
|---|---|---|---|
| ¼ acre | 10,890 | 1,012 | Typical suburban lot, ~66 × 165 ft |
| ½ acre | 21,780 | 2,023 | Large suburban lot |
| 1 acre | 43,560 | 4,047 | 208.7 ft square; about a football field without end zones |
| 2 acres | 87,120 | 8,094 | Small homestead |
| 5 acres | 217,800 | 20,234 | Hobby farm, horse property |
| 10 acres | 435,600 | 40,469 | Small subdivision or farm |
| 1 hectare | 107,639 | 10,000 | 2.47 acres; 100 × 100 m |
Source: Unit definitions (NIST SP 811; international acre 4,046.8564224 m²) · verified 2026-08-22
How land area is calculated
rectangle = width × depth · triangle (Heron) = √(s(s−a)(s−b)(s−c)) · four sides (Bretschneider) = √((s−a)(s−b)(s−c)(s−d) − abcd·cos²((A+C)/2)) · 1 acre = 43,560 ft² = 4,046.86 m²
A lot 100 ft wide and 200 ft deep: 100 × 200 = 20,000 ft². 20,000 ÷ 43,560 = 0.459 acres = 1,858 m² = 0.186 ha.
- Four-sided lots without angles use the cyclic-quadrilateral approximation; deeds list bearings — enter the angles for an exact figure.
- Areas are planimetric (flat map area), which is how deeds and the cadastre report them; sloped ground has more surface.
- For an irregular polygon the planner uses the shoelace formula on the drawn vertices.
What people use it for
Checking a listing
Listings round up. Enter the dimensions from the survey or plat to see whether "half an acre" is really 0.42.
Sizing a septic or well setback
Minimum lot sizes for private wells and septic systems are often 1 acre or more; confirm before you buy.
Subdividing
Divide the area by the local minimum lot size to see how many parcels are possible before roads and setbacks.
Fencing and seeding
Area drives seed, sod and fertilizer quantities; perimeter drives fencing.
Frequently asked questions
How many square feet are in an acre?
43,560 square feet. A square acre is 208.71 ft on each side.
How many acres is 20,000 square feet?
20,000 ÷ 43,560 = 0.459 acres, about 1,858 m².
How big is half an acre?
21,780 ft² or 2,023 m² — for example 100 × 218 ft or a 147 ft square.
How do I calculate acreage from lot dimensions?
Multiply width by depth in feet and divide by 43,560. For a triangle or an irregular four-sided lot use the side formulas above, or draw the lot.
How many acres is a hectare?
One hectare is 2.471 acres (10,000 m²). One acre is 0.4047 ha.
How many lots per acre?
Gross: 43,560 ÷ minimum lot size in ft². Net is 20–30 % less after streets and setbacks — the planner subdivision template shows both.
What is a quarter acre in square feet?
10,890 ft² (1,012 m²). A typical lot is about 66 × 165 ft.
Related tools
Sources and author
Terramify editorial team · Research and data verification · Updated August 22, 2026
Source: Unit definitions (NIST SP 811; international acre 4,046.8564224 m²)
Indicative estimate · not a survey or a design · see methodology