How to use this calculator
Choose a shape and enter its dimensions in one consistent unit. A triangle takes three side lengths; trapezoid height is perpendicular.
Formula and method
Rectangle A=wh. Circle A=πr². Triangle uses Heron’s formula. Isosceles trapezoid A=(b₁+b₂)h/2. Corner cutout A=WH−wh.
Worked example
A 6 m by 4 m rectangle has area 24 m² and perimeter 20 m.
Assumptions and supported scope
Positive dimensions. Triangle requires strict triangle inequalities; trapezoid assumes equal legs. Cutout is one corner, fully inside the rectangle. No arbitrary composite shape editor or automatic unit conversion; the result shows formula working without a shape diagram.
Method references
Method and worked example checked against the calculator implementation. About our methods · Report a correction