Sizu Riatto
Book 4 · Garden Math

Garden Area Calculator

An irregular garden is just simple shapes added together. List each piece, mark the ones that come out — patio, pond, shed — and you get the net growing area every other garden calculation starts from.

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Enter dimensions in feet. For a circle or half-circle put the radius in the first box (half the width across). Tick subtract for anything you are taking away.

PieceShapeLength / radiusWidth / heightSubtract?Area
Fill in at least one piece and press Total the area.
From the book — Chapter 1. A rectangle is length × width. A triangle is base × height ÷ 2. A circle is π × radius², and a half-circle is half of that. Anything awkward gets broken into pieces you can do, then added up — and anything you cannot plant in gets subtracted. A trapezoidal bed has no button of its own: average its two parallel sides and enter that as a rectangle against the height, which is exactly what (a + b) ÷ 2 × h means. This calculator uses π = 3.14, the same value the book does.

1 sq ft = 144 sq in · 1 sq yd = 9 sq ft · 1 acre = 43,560 sq ft. Everything stays in your browser.