Free field measurement
Acreage calculator
Draw your field on a satellite map and get its area in acres, square feet, hectares and square metres, with the perimeter. Then check what grows on it.
Measure your field
Find the field, open Draw Area, click each corner, then press Finish polygon. Drag corners with Edit Shape to adjust.
Draw a field or enter length and width to see its area.
Draw the field on the map to check what grows on it: soil, climate and crop fit for that exact boundary.
How to calculate acreage
Acreage is area in square feet divided by 43,560, the number of square feet in one acre:
acres = square feet ÷ 43,560
- Rectangle: multiply length by width in feet. 660 ft × 330 ft = 217,800 sq ft ÷ 43,560 = 5 acres.
- Triangle: ½ × base × height. A corner of 300 ft by 200 ft is 30,000 sq ft, about 0.69 acres.
- Irregular field: split it into rectangles and triangles, add their areas, then divide by 43,560. Or draw the outline on the map above, which measures any shape directly.
- Metric: square metres ÷ 4,046.86 gives acres; square metres ÷ 10,000 gives hectares.
The map tool measures the drawn shape on the Earth’s surface rather than on a flat projection, so large fields are not inflated the way a web-map’s pixel grid would inflate them. Perimeter is the sum of the edge lengths you drew.
How big is an acre?
One acre is 43,560 square feet, or 4,046.86 square metres. An acre has no fixed shape; any area of that size is one acre.
- A square 208.7 ft on each side
- 1 acre (208.71² ≈ 43,560 sq ft)
- A U.S. football field with end zones, 360 × 160 ft
- 57,600 sq ft ≈ 1.32 acres
- The same field between the goal lines, 300 × 160 ft
- 48,000 sq ft ≈ 1.10 acres
- One hectare, 100 × 100 m
- 10,000 m² ≈ 2.47 acres
- A quarter-mile square, 1,320 × 1,320 ft
- 40 acres
Sources: acre definition from NIST unit conversion factors; football field size from the NFL Rulebook, Rule 1 (360 × 160 ft). The other figures are arithmetic.
Know the size, not the potential?
A field audit checks soil, climate and crop fit for the boundary you drew, and ranks crops for that ground.
Acreage questions
How do you calculate acreage?
Find the area in square feet, then divide by 43,560. A rectangle is length × width, so a 660 ft × 330 ft field is 217,800 sq ft, or exactly 5 acres. Working in metres, divide square metres by 4,046.86 for acres or by 10,000 for hectares.
How big is an acre?
One acre is 43,560 square feet, or about 4,046.86 square metres. As a square it is about 208.7 feet on each side. A U.S. football field including both end zones (360 × 160 ft) is about 1.32 acres.
How do I measure an irregularly shaped field?
Draw it on the map above by clicking each corner. The calculator measures the area of the shape on the Earth’s surface, so it handles any number of sides. By hand, split the field into rectangles and triangles (½ × base × height), add the areas and divide by 43,560.
How accurate is a map measurement?
It is as accurate as the corners you click and the imagery under them. Zoom in to place corners on the actual boundary. For a sale, lease or a government programme, the legal survey or official record controls, not a drawn outline.
How many square feet are in an acre?
43,560 square feet. NIST lists the acre as 43,560 ft², which is 4,046.856 m² using the international foot.