Acreage Calculator
Find the acreage of a lot, field or yard two ways: outline it on a satellite map, or enter its sides, including irregular triangles and four-sided lots.
Acres = square feet ÷ 43,560. A rectangle 208.7 ft on each side is almost exactly 1 acre. For a lot with uneven sides, split it into triangles with a diagonal and use Heron's formula for each, or outline it on the map above. A quarter acre is 10,890 sq ft and a half acre is 21,780 sq ft.
Option 1: draw your lot on the map
Search an address, switch to satellite view, and tap each corner of the property in order. Drag corners to fine-tune.
Option 2: enter the measurements
Common lot sizes
| Acres | Square feet | Square yards | Example square lot |
|---|---|---|---|
| 0.1 | 4,356 | 484 | 66.0 × 66.0 ft |
| 0.25 | 10,890 | 1,210 | 104.4 × 104.4 ft |
| 0.5 | 21,780 | 2,420 | 147.6 × 147.6 ft |
| 1 | 43,560 | 4,840 | 208.7 × 208.7 ft |
| 2 | 87,120 | 9,680 | 295.2 × 295.2 ft |
| 5 | 217,800 | 24,200 | 466.7 × 466.7 ft |
| 10 | 435,600 | 48,400 | 660.0 × 660.0 ft |
Getting an accurate number
- Map outlines are only as good as the imagery and your clicks; expect a few percent of error. They are perfect for planning a garden, fence or seeding job.
- Four-sided lots need a diagonal: four sides alone do not fix the shape, which is why "average the opposite sides" shortcuts can be badly off.
- Legal acreage comes from your deed, plat or a licensed surveyor; county GIS parcel viewers often show it too.
Frequently asked questions
How do I calculate acreage?
Find the area in square feet and divide by 43,560. For a rectangle, multiply length × width in feet. For an irregular lot, split it into triangles, find each triangle's area and add them, or outline the lot on a map tool.
How many square feet are in an acre?
43,560 square feet, or 4,840 square yards. A square acre is about 208.7 ft on each side.
How do I find the acreage of an irregular lot?
Measure all the sides and one diagonal, which splits the lot into two triangles. Heron's formula gives each triangle's area from its three sides. Add them and divide by 43,560. Or outline the lot on the satellite map.
Can I measure acreage with Google Maps?
Google Maps measures distance but not area on its own. This tool lets you outline an area on satellite imagery and calculates the area of the shape using the curvature of the Earth.
How big is a quarter acre?
10,890 square feet, about 104 × 104 ft, or a typical suburban lot of about 70 × 155 ft.
Run a garden club, nursery or landscaping site? Embed this calculator free with one line of code.
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Map area uses the geodesic polygon formula on the WGS84 sphere (the same method as Leaflet.draw). Satellite imagery: USGS National Map (public domain); street map © OpenStreetMap contributors; address search by OpenStreetMap Nominatim. Triangles use Heron's formula. 1 acre = 43,560 sq ft = 0.404686 ha.