How to use this calculator
Add rectangle, circle or triangle shapes, choose feet or metres and enter each shape’s dimensions. Review total area and the material quantities and prices you supply.
How to use the result
A rectangle has area length × width, a circle has area π × radius², and a triangle has area base × height ÷ 2. Areas are added in the selected unit system.
The triangle perimeter assumes an isosceles triangle: each equal side is computed from half the base and the height. Flooring and paint estimates use the selected coverage, prices and room assumptions.
Assumptions and limits
Do not mix dimension units within one calculation. A floor-area estimate is not a measured building plan, and the triangle perimeter does not describe every possible triangle. Check actual material coverage and allow separately for cutting waste, surface preparation and product-specific coat requirements.
Worked example
A 12 ft by 10 ft rectangle has an area of 120 square feet. A separate 6 ft by 4 ft rectangle adds 24 square feet, giving 144 square feet in total.