Area Calculator – Rectangle, Triangle, Circle & More
Find the area of common shapes with the right formula for each.
- Free
- Instant result
- Private · on-device
- No sign-up
How to use: Pick a shape, enter the dimensions, and read the area in square units.
How to use the Area Calculator
Pick a shape: rectangle, square, triangle, circle, trapezoid, or parallelogram. Enter the dimensions in any consistent unit—metres, feet, or inches—and the calculator returns area in that unit squared using the standard geometric formulas.
Rectangle and square use length × width (or side²). Triangle uses base × height ÷ 2. Circle uses πr². Trapezoid averages the two parallel sides and multiplies by height. Parallelogram is base × height. Keep units consistent so you do not mix feet with metres.
For flooring, paint, or garden beds, measure carefully and round up slightly for waste. Convert units afterward with our unit converter if your supplier lists materials in a different system.
This tool is for flat 2D shapes. It does not compute surface area of 3D solids or irregular polygons with many sides; break complex floor plans into rectangles and triangles and add the pieces.
Students can verify homework, and DIYers can estimate material quantities quickly. Pair with the fraction calculator when a sketch gives mixed-number measurements.
Frequently asked questions
What is the area of a circle?
π times radius squared (πr²).
How do I find triangle area?
Half of base times height (½bh), with height perpendicular to the base.
Can I calculate land area?
Yes for rectangular or triangular lots if you have survey lengths — irregular plots need more advanced methods.
Does order of length and width matter?
Not for rectangles; area is the product either way.