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Area and perimeter calculator

Calculate the area and perimeter of squares, rectangles, circles, triangles and more.

Input
Output
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Area and perimeter calculator
Paste one or more shapes' dimensions and this tool calculates the perimeter and area for each line, along with a running total. It covers nine shapes: square, rectangle, circle, circular sector, triangle, trapezoid, rhombus, regular polygon and ellipse. Enter each shape's dimensions on its own line, separated by semicolons — a rectangle is width;height, a triangle is three side lengths, a circular sector is radius;angle in degrees. This makes it useful for estimating flooring, paint, fencing, land plots or fabric from a list of measurements in one pass rather than one shape at a time.
Pick the shape first, since every line in the input is read with that shape's formula. The length unit applies to every dimension you enter and to the output: choose millimeters, centimeters, meters, inches or feet, and the area is labeled with the matching squared unit automatically — no separate conversion step needed. Decimal places controls how many digits the results are rounded to, and "Show intermediate steps" expands each result into the substituted calculation, not just the formula and the answer — useful for checking the arithmetic or explaining it to someone else.
Setting a price per square meter adds a material cost line to the total, converted to square meters regardless of which unit you entered dimensions in, which is handy for estimating tiling, turf or paint jobs priced by area. Output format switches between a readable text report and a tab-separated table that pastes cleanly into a spreadsheet. Invalid input — the wrong number of values for the selected shape, a non-numeric entry, a zero or negative dimension, or three sides that can't form a triangle — is reported with the exact line number so you can fix one row without losing the rest.
Everything runs locally in your browser; no dimensions or measurements are ever uploaded. Copy the result, download it as a .txt file, or send the output back into the input to keep adjusting a set of measurements.
FAQ
How do I enter dimensions for each shape?
Separate values with a semicolon, one shape per line. A rectangle is width;height (e.g. 3;4), a circle is just the radius, and a triangle is three side lengths. The option list next to "Shape" shows the exact order for each one.
Can I mix different shapes in one input?
No — every line is read using the shape currently selected in the options. To total shapes of different kinds, run the calculation once per shape and add the totals yourself.
How does the unit conversion work?
The length unit you pick applies to every dimension you type in and labels the results — pick "m" and areas come out in m², pick "ft" and they come out in ft². It does not convert between units; it labels and sums consistently in the one you choose.
What does the material cost option calculate?
Set a price per square meter and the tool converts the total area to square meters (whatever unit you entered dimensions in) and multiplies it by that price, giving a rough material cost alongside the totals.
Is my data uploaded anywhere?
No. All calculations run entirely in your browser — your measurements are never sent to a server.