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Measure your area correctly

Rectangle, triangle, circle, trapezoid — and composite areas

2026-06-14·5 min reading

An accurately measured area is the starting point for plant, soil and material quantities. Here is how to measure the four basic shapes and add them up into a composite area.

Introduction

Almost all material quantities start with an area: plants, topsoil, gravel, paving slabs, seed and fertiliser are all calculated from m². A careful survey is therefore the single most important part of an estimate.

LBA = L · BbaselineheightA = ½ · g · hrA = π · r²abhA = ½ · (a + b) · h
Fig. The Four Basic Shapes — rectangle, triangle, circle and trapezoid — with the area formula for each.

Compound areas

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