📐 Area Calculator
Area measures the size of a flat surface — how much paint a wall needs, how much flooring a room takes, or how much land a plot covers. Choose the shape and enter its dimensions below.
Keep every measurement in the same unit: metres with metres give square metres. Convert first if your length and width were measured in different units.
How to use this calculator
Choose the shape card - rectangle, triangle or circle - and enter its measurements. Each card returns the area in one click.
- Pick the right card for your shape: Rectangle, Triangle or Circle.
- Fill in the card's fields, such as Length and Width for the rectangle, or just Radius for the circle.
- Keep all measurements in the same unit so the square unit of the answer stays consistent.
- Press Calculate and read the area; change a measurement and recalculate to compare sizes.
Frequently asked questions
Which shapes does this area calculator cover?
The page covers three flat shapes: a rectangle from length and width, a triangle from base and height, and a circle from radius. Each shape is a separate card with its own fields.
What formulas does it use?
The rectangle multiplies length times width; the triangle uses half times base times height; the circle uses pi times radius squared.
Can you show a worked example?
On the circle card, enter a radius of 5: pi times 25 gives about 78.54 square units of area.
Any practical tip for measuring area?
For the triangle, the height must be measured perpendicular to the base - a slanted side gives an inflated, wrong answer. For painting or flooring estimates, add about 10 percent extra for cutting and waste.