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Garden Area Calculator

Measure Lawns, Circles, Triangles and L-Shapes in Square Metres, Feet and Acres

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How the Garden Area Calculator works

This garden area calculator measures a lawn, bed or whole plot in square metres, square feet, square yards and acres. Pick the shape closest to your garden, enter the sides in metres or in feet and inches such as 32'6", and it returns the area ready for ordering turf, seed, fertiliser, mulch or paving.

Most gardens are not perfect rectangles, but nearly all can be broken into simple shapes. An L-shaped lawn is two rectangles added together; a round bed is a circle; a corner bed is a triangle. For a plot whose four sides are all different lengths, measuring each side gives a good estimate as long as the corners are close to square.

How the garden area calculator works

Each shape has its own formula. A rectangle is length × width, a circle is π × diameter² ÷ 4, and a triangle is base × height ÷ 2. For four unequal sides the calculator averages the opposite pairs: (side 1 + side 3) ÷ 2 × (side 2 + side 4) ÷ 2. For example, a lawn of 10 m by 6 m is 60 m², or 646 ft². A second example: a plot with sides of 12, 8, 11 and 9 m is 11.5 × 8.5 = 97.75 m².

The four-sides method is close for plots that are almost rectangular. For a very skewed plot, split it along a diagonal into two triangles, measure each triangle's base and height, and add the two results. For a curved edge, lay a hose along it and measure the straight sections it forms.

To see how many square metres of turf or how many bags of seed to buy, take the area and add 5–10% for cutting and edges. One acre is 4,047 m² or 43,560 ft², and one hectare is 10,000 m².

Area of common rectangular garden sizes in square metres, square feet and square yards

Size (m) m² ft² yd²
3 × 3 9 97 11
4 × 3 12 129 14
4 × 4 16 172 19
5 × 4 20 215 24
6 × 4 24 258 29
6 × 5 30 323 36
8 × 5 40 431 48
8 × 6 48 517 57
10 × 5 50 538 60
10 × 6 60 646 72
10 × 8 80 861 96
10 × 10 100 1,076 120
12 × 8 96 1,033 115
12 × 10 120 1,292 144
15 × 10 150 1,615 179
15 × 12 180 1,938 215
20 × 10 200 2,153 239
20 × 15 300 3,229 359
25 × 10 250 2,691 299
30 × 10 300 3,229 359
30 × 20 600 6,458 718
40 × 25 1,000 10,764 1,196

FAQ

How do I measure an irregular shaped garden?

Break it into rectangles, triangles and circles, measure each part and add the areas. For a plot with four uneven sides, measure all four and use the four-sides option, which averages opposite sides. The more nearly square the corners are, the closer that estimate will be.

How many square metres is an average garden?

Back gardens vary widely by country and age of house. A typical new-build garden in England is around 50–100 m², older suburban plots are often 150–300 m², and US suburban lots commonly have 500 m² or more of yard. Measure your own for anything you plan to buy.

How do I convert square feet to square metres?

Divide square feet by 10.764, or multiply by 0.0929. So 500 ft² is about 46.5 m². To go the other way, multiply square metres by 10.764. One square yard is exactly 9 square feet, which is about 0.836 m².

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