Lawn Area Calculator

How it works

Few lawns are a single rectangle, but most can be broken into rectangles, circles and triangles. Each shape's area comes from its standard formula: length times width, π times the radius squared, and half the base times the height (the height measured square to the base). The shapes are added up.

Areas inside those shapes that are not lawn, such as the house footprint, a driveway, a patio or a round bed, are listed as excluded rectangles and circles and subtracted. The result is the lawn area in your unit, in square feet, in acres (43,560 sq ft each) and in 1,000 sq ft units, the unit seed and fertilizer rates are usually given in.

Formula

rectangle = length × width
circle    = π × radius²
triangle  = ½ × base × height
lawn      = Σ shapes − Σ excluded rectangles and circles
acres     = sq ft ÷ 43,560;  1,000 sq ft units = sq ft ÷ 1,000

Example

A front lawn of 60 × 40 ft (2,400 sq ft) and a back lawn of 80 × 50 ft (4,000 sq ft), plus a round area of radius 6 ft (113.10 sq ft) and a triangular corner with a 30 ft base and 20 ft height (300 sq ft), total 6,813.10 sq ft.

Excluding a 30 × 20 ft patio (600 sq ft) and a round bed of radius 4 ft (50.27 sq ft) leaves 6,162.83 sq ft of lawn, 0.141479 acres or 6.163 units of 1,000 sq ft.

Assumptions and limitations

• Each shape is treated as flat and exact. Slopes have more surface than their plan area; curved edges that are not circles are approximated by the shapes chosen. The irregular lawn area calculator handles curved outlines from offset measurements.
• Excluded areas are assumed to lie inside the shapes listed; the calculator does not know where shapes are and cannot detect overlaps between them.
• A triangle's height is the perpendicular distance from the base to the opposite corner, not the length of a sloping side.
• Product rates per 1,000 sq ft come from the product label or an extension guide; this calculator gives only the area they apply to.

Frequently asked questions