Lawn area calculator

Almost every product for a lawn — seed, fertilizer, sod, weed control — is dosed by area. Add as many rows as you need, and leave the circle and triangle rows blank if you don’t need them.

How to measure an irregular yard

You don’t need a survey. Purdue Extension’s sod guide recommends exactly this: divide the lawn into squares, rectangles and circles, work out each one, and add them together — or measure the whole property and subtract the house, drive and other hard surfaces. Treat curved corners as triangles or part-circles. Small errors mostly cancel out, and for seed or fertilizer a few percent either way doesn’t matter.

rectangle = length × width
circle = 3.1416 × (diameter ÷ 2)²
triangle = base × height ÷ 2
1 acre = 43,560 sq ft · 1,000 sq ft ≈ 92.9 m² · 1 hectare = 10,000 m²

Step by step

1. Walk the yard with a tape or measuring wheel and sketch the outline on paper.
2. Draw the biggest rectangle you can fit inside it and measure that first.
3. Add a row for each smaller rectangle: side yards, the strip by the drive, the patch behind the garage. Use a triangle for a wedge-shaped corner (height is measured at right angles to the base) and a circle for round areas.
4. Subtract the footprint of the house, driveway, patio and planting beds if they fall inside your shapes.
5. Write the answer on the sketch. You will use it every season.

What to do with the number

Under the result there are links that open the seed, fertilizer, lime, sod, topsoil and compost calculators with your area already filled in. For seed, compare it with how much grass seed for 1,000 sq ft of tall fescue, or, for a whole lot, how much grass seed for a 1/4 acre. Measuring in metric? See how much grass seed for 100 m². For sod, add the waste allowance in the sod calculator.

The same shape method works for planting beds. Add up the beds instead of the grass for mulch or pine straw: how much pine straw for 1,000 sq ft of beds shows what a typical house’s beds take.