Plot area from measured sides or corner coordinates, in metric and US units at once.
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Most plots of land are not neat rectangles, but almost any plot can be measured as a set of triangles. Enter the length and width of a rectangular plot, the three sides of a triangle, the dimensions of an L-shape, the four sides and one diagonal of a four-sided plot, or the coordinates of every corner; the calculator returns the area in square metres, square feet, square yards, acres and hectares. The guide below works a real-shaped plot two ways, gives the exact acre and hectare conversions, and explains the two mistakes that most often inflate a measured area: measuring along a slope and assuming corners are square.
Select the shape: rectangle, triangle, L-shape, four sides with a diagonal, or corner coordinates.
Enter the measurements in metres or feet — horizontal distances, not along a slope.
Click Calculate to see the area in m², ft², square yards, acres and hectares.
By O.E. — Partner, chairman of the board and CEO of a metal products manufacturer for 21 years; the company exports to 45 countries.
Drafted with AI assistance; calculations checked against primary sources and tested with the site's own code. About FlowUtil
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Rectangle: L × W. Triangle from three sides (Heron): √(s(s−a)(s−b)(s−c)), s = (a+b+c)/2 — no angles needed, which is why it suits tape measurements. L-shape: full rectangle minus the cut-out. Four sides and one diagonal: two Heron triangles. Corner coordinates (shoelace): ½ |Σ (xᵢ yᵢ₊₁ − xᵢ₊₁ yᵢ)| for any polygon whose sides do not cross, with as many corners as you like.
1Corners at (0, 0), (62, 0), (70, 41) and (8, 47) metres.
½ × |0 + 2,542 + 2,962 + 0|
2,752 m² = 0.2752 ha = 0.680 acres = 29,622 ft²
2The same plot by tape: sides 62.00, 41.77, 62.29 and 47.68 m, and the diagonal from the first to the third corner, 81.12 m.
Heron: 1,270.91 + 1,481.15
2,752.06 m²
Four sides alone are not enough — a four-sided shape with fixed sides can lean like a parallelogram, changing its area. One diagonal fixes it.
3A 50 m × 30 m rectangle; a right-triangular corner with sides 30, 40 and 50 ft.
L × W · Heron
1,500 m² = 0.15 ha = 0.3707 acres · 600 ft² (55.7 m²)
| Unit | Square metres | Square feet |
|---|---|---|
| 1 hectare | 10,000 | 107,639 |
| 1 acre | 4,046.8564224 | 43,560 |
| 1 square yard | 0.83612736 | 9 |
One hectare is 2.471 acres; one acre is a square about 63.6 m (208.7 ft) on a side. Until the end of 2022 US land measurements could be based on the US survey foot, which made an acre 4,046.873 m². NIST and the National Geodetic Survey have since retired the survey foot, so the international foot (exactly 0.3048 m) applies; older deeds and state plane coordinates may still use the survey foot.
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