Area Calculator

Find the area and perimeter of any shape in seconds — rectangle, square, circle, triangle, trapezoid or parallelogram. Enter the measurements, get instant results. Everything runs in your browser; no signup, no data leaves your device.

By UpnixTools · Calculator and figures last reviewed November 2026

Shape & Measurements

Area = length × widthPerimeter = 2 × (length + width)

Tip: measure every side in the same unit. The result updates live as you type.

Your Result

Area
—
Rectangle
Perimeter—
Formula usedL × W
Area in m²—
Area in ft²—

Area tells you how much surface a shape covers — useful for flooring, painting, garden beds and fabric. Perimeter is the total length around the outside edge.

How to use this area calculator

  1. Pick a shape from the tabs above — rectangle, square, circle, triangle, trapezoid or parallelogram.
  2. Choose your unit (cm, m, inches or feet) and enter the measurements shown.
  3. Read the result — the area and perimeter update instantly, with automatic conversions to m² and ft².

Area formulas for every shape

RectangleL × W
Squareside²
Circleπ × r²
Triangle½ × base × height
Trapezoid½ × (a + b) × h
Parallelogrambase × height

Area vs. perimeter — what's the difference?

Area measures the surface inside a shape, in square units (cm², m², ft²). Perimeter measures the distance around the outside, in plain units (cm, m, ft). Two shapes can share the same perimeter but have very different areas — a long thin rectangle, for example, encloses far less area than a square with the same perimeter.

Area Calculator FAQs

How do you calculate the area of a rectangle?
Multiply the length by the width: Area = length × width. A rectangle 10 cm long and 6 cm wide has an area of 60 cm². Its perimeter is 2 × (length + width), which is 32 cm in this example.
What is the formula for the area of a circle?
Area = π × radius². For a circle with a radius of 5 cm, the area is about 78.54 cm². The perimeter of a circle is called the circumference: 2 × π × radius, which is about 31.42 cm for the same circle.
How do you find the area of a triangle?
Area = ½ × base × height, where the height is measured straight up from the base at a right angle. A triangle with a base of 8 cm and a height of 5 cm has an area of 20 cm². The perimeter is simply the sum of all three sides.
What units should I use for area?
Use the same unit for every measurement, and the area comes out in square units of that unit — cm² for centimeters, m² for meters, in² for inches and ft² for feet. This calculator also converts your result into square meters and square feet automatically.
Is this area calculator free and private?
Yes. It is completely free, needs no signup, and runs entirely in your browser. Your measurements are never sent to a server.

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