Area Calculator
Calculate the area of rectangles, squares, circles and triangles with common unit conversions.
Area
How we calculated it
About the Area Calculator
Surface-area problems become much simpler once the outline is matched to the right geometric formula. This calculator handles common two-dimensional shapes and converts the result into the square unit needed for the task.
Choosing the correct shape is more important than carrying many decimal places. For irregular outlines, divide the area into simpler pieces instead of forcing one formula to fit.
How to Use the Area Calculator
- Choose the geometric shape that matches the section you are measuring.
- Enter the required dimensions, such as length and width, base and height or radius.
- Keep length units consistent before calculating.
- For a compound shape, calculate the pieces separately and add or subtract their areas as appropriate.
How the Calculation Works
Each shape uses its own geometric formula: rectangle A = length × width, triangle A = base × height ÷ 2 and circle A = πr², with corresponding formulas for other supported shapes.
Length units are normalized before the formula is applied, and the result is converted to the selected square unit.
Worked example
Area Calculator Worked Example
Triangle with 12 m base and 7 m height
Area = 12 × 7 ÷ 2 = 42 m². The height must be perpendicular to the base; using a sloping side length as the height would produce the wrong area.
Result guide
Understanding Your Area Calculator Result
Area measures a two-dimensional surface. It should not be confused with perimeter, which measures boundary length, or volume, which includes a third dimension.
Before you rely on the answer
Assumptions and Limitations
- The selected formula matches the actual shape.
- Measurements use compatible units.
- Required heights are perpendicular where the formula assumes they are.
Practical tip
Using This Result in Practice
For real rooms, gardens or lots, sketch the outline and label the dimensions before calculating. Visualizing the pieces helps prevent double-counting or missing an inset.
Related calculations
Useful Calculations to Continue With
If the object has depth or height and you need three-dimensional capacity, continue with the Volume Calculator.
If your goal is specifically building or floor area in square feet, the Square Footage Calculator offers a more project-oriented workflow.
Common questions
Area Calculator FAQ
What is the difference between area and perimeter?
Area measures the surface inside a shape, while perimeter measures the distance around its boundary.
Why are area units squared?
Area comes from multiplying two lengths, so feet × feet becomes square feet and metres × metres becomes square metres.
How do I find the area of an irregular shape?
Break it into regular shapes, calculate each area and then add or subtract the pieces.