Area Calculator
Choose a shape, enter its measurements and get the area in square metres, feet, yards, acres and hectares.
What this tool does
To find an area, choose the shape, enter its measurements and pick the unit. The calculator applies the right formula - length × width for a rectangle, half base × height for a triangle, π × radius² for a circle - and shows the area in square metres, square feet, acres and more.
Applies the standard area formula for the shape you choose.
Converts the result into common area units using exact factors.
How to use it
- Choose the shape.
- Enter A, B and C as described next to the shape.
- Choose the length unit.
- Read the area and the conversions.
Why use this calculator
Calculates the area of six common shapes and shows the result in square metres, feet, inches, yards, hectares and acres. Area is needed for flooring, paint, land, fabric and homework, and the formula differs for every shape. Having them in one place with the conversions avoids both mistakes and extra steps.
Why we built it
We built the area calculator for six common shapes with the answer in square metres, feet, inches, yards, hectares and acres, so one measurement serves every supplier. The square footage calculator adds up several rooms, and the perimeter calculator gives the distance around.
If your task goes further, try the Circle Calculator.
Related tools worth a look: the Surface Area Calculator.
Who this tool is for
- Homeowners measuring rooms and gardens
- Students doing geometry
- Builders pricing floors and turf
When to use it
- Estimating materials for a floor, wall or garden.
- Working out the size of a plot of land.
- Maths and science homework.
- Converting between metric and imperial areas.
How it works
Rectangle and parallelogram: base × height. Triangle: ½ × base × height. Circle: π × r². Trapezoid: ½ × (a + b) × height. Ellipse: π × a × b, where a and b are the two radii.
The result is computed in the unit you pick and also converted to square metres: for example a 10 ft by 10 ft square is 100 sq ft = 9.2903 m².
Give every measurement in the same unit. Areas are always in squared units of the unit you chose.
A worked example
These are the values the calculator opens with, so you can see exactly what it does with them. Change any value on the page and the result updates; the figures below come from the same calculation.
| Input | Value |
|---|---|
| Shape | Rectangle (A = length, B = width) |
| A | 5 |
| B | 4 |
| C | 3 |
| Unit | Metres |
With those inputs, the calculator returns:
- Area: 20 m²
- Square metres: 20
- Square feet: 215.2782
- Square inches: 31,000.06
- Square yards: 23.9198
- Hectares: 0.002
- Acres: 0.004942
What you give it, and what you get back
| Item | Details |
|---|---|
| Shape | Rectangle, triangle, circle, trapezoid, parallelogram or ellipse. |
| A, B, C | The measurements the shape needs, as described beside the shape name. |
| Unit | Length unit from millimetres to kilometres, inches, feet or yards. |
| Result | Area in your unit squared, plus m², sq ft, sq in, sq yd, hectares and acres. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| "Enter positive numbers" | A required measurement is 0 or empty. | Fill in A (and B or C when the shape needs them). |
| Result in wrong unit | The unit selection is different from your measurements. | Choose the correct unit. |
| Circle given diameter | The circle needs the radius. | Halve the diameter first, or use the circle calculator. |
| Irregular shape | Only the six shapes are supported. | Split it into simple shapes and add the areas. |
Assumptions and limitations
- Six standard shapes only.
- Flat (2D) areas, not surface areas of 3D objects.
- One unit for all measurements.
Frequently asked questions
How do I calculate the area of a rectangle?
Multiply the length by the width.
How do I calculate the area of a circle?
Multiply π (3.14159) by the radius squared.
How do I find the area of a triangle?
Multiply the base by the height and divide by 2.
What is the area of a trapezoid?
Add the two parallel sides, multiply by the height and divide by 2.
How do I convert square feet to acres?
Divide by 43,560.
Does it send my numbers anywhere?
No. It calculates in your browser.