Area Calculator

How area is calculated

Pick a shape, enter its dimensions in any length unit, and the calculator applies the standard geometry formula, converts the result to square meters, and then to whichever area unit you want — from square centimeters to acres and hectares.

Formulas

Rectangle: A = length × width

Square: A = side²

Circle: A = π × radius²

Triangle: A = base × height ÷ 2

Trapezoid: A = (base₁ + base₂) ÷ 2 × height

Ellipse: A = π × radius₁ × radius₂

Worked examples

• Room 12 m × 8 m — 96 m², which is about 1,033 sq ft.
• Circle with 5 m radius — π × 25 ≈ 78.54 m².
• Triangle, base 10 m, height 6 m — 10 × 6 ÷ 2 = 30 m².
• Plot 50 m × 80 m in acres — 4,000 m² ÷ 4,046.86 ≈ 0.99 acre.

Everyday reasons to measure area

• Flooring and tiling — how many square metres of laminate, carpet, or tile a room needs.
• Paint — wall area divided by a tin's coverage (often 10–12 m² per litre) tells you how much to buy.
• Land and gardens — the size of a plot, lawn, or patio in square metres, acres, or hectares.
• Fabric and materials — estimating sheet goods, turf, or wallpaper for a project.

Handling irregular shapes and waste

A space that is not a neat rectangle can usually be split into simpler shapes — rectangles, triangles, and circle segments — measured separately and added together. Subtract openings like doorways or a kitchen island from the total. For materials sold in whole units, add 5–10% for cutting waste and offcuts so you are not left short partway through the job.

Radius or diameter — the error that quadruples the answer

A circle's formula takes the radius, but a tape measure across a lawn, table or pool gives you the diameter. Feed the diameter in as the radius and the result is four times too large, because area scales with the square. Measure across the widest point, halve it, then square it.

The same squaring is why small measuring errors grow: a 10% overestimate on each side of a room becomes a 21% overestimate of the flooring order.

Common room sizes at a glance

Useful for sanity-checking a measurement, or for reading a listing written in the other unit system.

Turning area into a quantity to buy

Materials are sold by coverage, not by area, so the last step is a division and a round-up. Typical coverage figures:

Always round up to whole units and add the waste allowance before ordering, not after. A 22 m² living room in laminate at 2.2 m² per pack is exactly 10 packs before waste — and 11 once 10% is added.

Measuring a plot that has no straight edges

For land, split the shape into triangles rather than rectangles: any polygon can be divided into triangles, and each needs only a base and a perpendicular height. For a genuinely curved boundary, overlay a grid, count the fully enclosed squares, and add half the count of the partly covered ones — crude, but it lands within a few percent and needs nothing but a plan and a pencil.

Perimeter and area answer different questions: fencing, skirting and edging are priced by perimeter, while turf, paving and paint are priced by area. Doubling a square's side doubles its perimeter but quadruples its area, so the two quotes do not move together.

For three-dimensional shapes — tanks, boxes, pools — use the volume calculator; for plain unit-to-unit area conversion, the unit converter.