Acreage calculator: square feet to acres and lot size
Divide square feet by 43,560 to get acres. A lot 250 feet long and 180 feet wide covers 45,000 square feet, which is 1.0331 acres, or about 0.42 hectares.
Inputs used by this calculator
Acreage Calculator uses the fields below. The starting values reproduce the page example; replace them with values from the same units and time period before using the result.
| Input | Starting example | Accepted value | How it is used |
|---|---|---|---|
| Start from | Lot length and width | Lot length and width · A known area | Selects the unit or conversion path used by Acreage Calculator. |
| Length | 250 | 0 to 1000000000 | Supplies the length quantity used by the published equation or result breakdown. |
| Width | 180 | 0 to 1000000000 | Supplies the width quantity used by the published equation or result breakdown. |
| Length unit | Feet | Feet · Yards · Meters | Selects the unit or conversion path used by Acreage Calculator. |
| Area | 43,560 | 0 to 1000000000000000 | Supplies the area quantity used by the published equation or result breakdown. |
| Area unit | Square feet | Square feet · Square yards · Square meters · 3 more choices | Selects the unit or conversion path used by Acreage Calculator. |
How big an acre is
An acre is 43,560 square feet, historically one chain (66 feet) by one furlong (660 feet). It has no required shape: a square acre is about 208.7 feet on each side. An American football field from goal line to goal line, 300 by 160 feet, covers 48,000 square feet, a little more than 1.1 acres.
Square feet to acres
Divide the area in square feet by 43,560. A 10,890 square-foot lot is exactly a quarter acre, and a 7,500 square-foot suburban lot is about 0.17 acres. To go the other way, multiply acres by 43,560.
acres = sq ft ÷ 43,560sq ft = acres × 43,560Finding acreage from lot dimensions
For a rectangular lot, multiply length by width in the same unit, then convert. Yards are squared too, so one square yard is 9 square feet; one meter is 3.2808 feet. Frontage and depth listed on a real-estate listing are usually in feet.
Irregular lots
Most lots are not perfect rectangles. The legal area is the one on the deed, plat or survey. For a rough estimate, split the lot into rectangles and right triangles, calculate each area, add them and convert the total. Curved boundaries and easements need a surveyor.
Hectares, square miles and sections
A hectare is 10,000 square meters, about 2.471 acres. A square mile is 640 acres, and in the Public Land Survey System a section is one square mile, divided into quarter sections of 160 acres. The calculator shows each of these units for the same area.
Survey foot versus international foot
Older U.S. land records used the survey foot, which is about two parts per million longer than the international foot. NIST and NOAA retired the survey foot at the end of 2022. The difference is about 0.17 square feet per acre, so it only matters for high-precision surveying.
Common lot sizes
| Lot size | Square feet | Square meters | Square side |
|---|---|---|---|
| 1/8 acre | 5,445 | 506 | 73.8 ft |
| 1/4 acre | 10,890 | 1,012 | 104.4 ft |
| 1/3 acre | 14,520 | 1,349 | 120.5 ft |
| 1/2 acre | 21,780 | 2,023 | 147.6 ft |
| 1 acre | 43,560 | 4,047 | 208.7 ft |
| 2 acres | 87,120 | 8,094 | 295.2 ft |
| 5 acres | 217,800 | 20,234 | 466.7 ft |
| 10 acres | 435,600 | 40,469 | 660.0 ft |
| 40 acres | 1,742,400 | 161,874 | 1320.0 ft |
Frequently asked questions
How many square feet are in an acre?
43,560 square feet.
How do I convert square feet to acres?
Divide by 43,560. For example, 20,000 square feet is about 0.46 acres.
How big is a quarter acre?
10,890 square feet, about 104.4 feet on each side if it were square.
How many acres is a football field?
The playing field between the goal lines is about 1.1 acres; with both end zones it is about 1.32 acres.
How many acres are in a hectare?
About 2.471 acres. One acre is about 0.405 hectares.
Can I use this for an irregular lot?
Only as an estimate built from simple shapes. The deed, plat or a surveyor gives the legal area.
How many acres are in a square mile?
640 acres.
What to keep in mind
Length times width is exact only for rectangles. Irregular lots need the surveyed area from the deed or plat, or a split into simple shapes.
Results are rounded for display in US format, with money in dollars and cents; CSV exports keep full calculation precision. This is a calculation summary, not an official certificate.