Area Calculator
Area and perimeter for six common shapes.
How to use
- 1 Choose the shape you want to measure.
- 2 Enter the dimensions the calculator asks for.
- 3 Read the area, and the perimeter where shown.
- 4 Copy the result with the copy button.
About Area Calculator
The Area Calculator works out the area of the six shapes you reach for most often: rectangle, square, triangle, circle, trapezoid and parallelogram.
Pick a shape, type in the dimensions it needs, and the result updates instantly as you type.
Where it makes sense the calculator also reports the perimeter, so you can size a fence, a frame or a border in the same step.
Each shape uses the standard formula you learned in school.
A rectangle is width times height; a triangle is half its base times its height; a circle is pi times the radius squared; a trapezoid averages its two parallel sides and multiplies by the height.
The tool validates your input, so if a value is missing or negative you get a clear, specific message instead of a confusing number.
Results are shown with sensible rounding and grouped digits for readability, and you can copy the area with one click.
Because My Tools Garage is privacy-first, every calculation runs entirely in your browser.
Nothing you enter is uploaded, logged or stored, and the calculator keeps working offline once the page has loaded — handy for the workshop, the classroom or the field.
FAQ
Which units does it use?
The calculator is unit-agnostic: enter your dimensions in any unit and the area comes back in that unit squared. Keep all inputs in the same unit for a correct result.
Why is there no perimeter for triangles and trapezoids?
Those perimeters need the slant or remaining side lengths, which the base-and-height inputs do not provide, so only the area is shown to avoid a misleading figure.