Area Calculator

How this calculator works

Choose a shape, enter its dimensions in feet, and the calculator applies the correct formula:

Shape	Formula	Inputs used
Rectangle	length × width	first two fields
Circle	π × radius²	first field (radius)
Triangle	½ × base × height	first two fields
Trapezoid	½ × (base₁ + base₂) × height	all three fields

Results are shown simultaneously in square feet, square metres, square yards, and acres, so a room measurement, a flooring quote in m², and a land listing in acres can all be compared without a second conversion step.

Worked example

A 12 ft × 8 ft room is 96 sq ft — about 8.9 m² or 10.7 sq yd. Planning flooring? Add a 10% waste allowance (≈106 sq ft) before ordering. A circular patio with a 12 ft radius, by contrast, covers about 452 sq ft — π does a lot of work.

Measuring real spaces well

• Irregular rooms: split the space into rectangles and triangles, calculate each, and add them up — an L-shaped room is just two rectangles.
• Circle inputs: the field asks for the radius. If you measured across the whole circle (the diameter), halve it first.
• Trapezoid sides: the two parallel sides are the bases; the height is the straight-line distance between them, not the slanted side length.
• Acres for land: one acre is 43,560 sq ft — roughly 75% of an American football field. The acres output makes small survey figures meaningful at a glance.

Frequently asked questions