Area Calculator
Calculate the area and perimeter of 2D shapes including squares, rectangles, circles, triangles, and more. Supports acres and hectares.
An area calculator computes the area and perimeter of common 2D shapes including squares, rectangles, circles, and triangles, with support for unit conversions to acres and hectares.
Examples
Room Area
Frequently Asked Questions
How many square feet are in an acre?
Quick Tips
- •Convert units to the same system before entering values.
- •For irregular shapes, break them into simpler shapes, calculate each area, and sum the results.
- •Double-check your inputs — small errors in length are squared in area calculations.
An area calculator computes the area and perimeter of common 2D shapes including squares, rectangles, circles, and triangles, with support for unit conversions to acres and hectares.
How to Use This Calculator
Select the 2D shape (e.g. square, rectangle, circle, triangle) from the dropdown. Choose your units (e.g. feet, meters). Enter the dimensions required for that shape (e.g. side length, radius, base and height). Click Calculate to see the area and, where applicable, the perimeter.
Understanding the Formula
Square: side². Rectangle: l × w. Circle: πr². Triangle: (base × height) / 2.
Examples
Room Area
A room that is 12ft by 15ft has an area of 180 sq. feet.
Frequently Asked Questions
How many square feet are in an acre?
One acre is exactly 43,560 square feet.
Assumptions & Limitations
- Assumes exact input dimensions — rounding errors in measurements will propagate to the result.
- All shapes are treated as ideal geometric figures with perfectly straight sides or smooth curves.
- Unit conversions use standard definitions (e.g., 1 acre = 43,560 sq ft).