Measure a rectangular room
Multiply length by width. A room 12 feet long and 10 feet wide has an area of 120 square feet, or about 11.1483648 square meters. Measure each dimension in the same units before calculating.
Area & Square Footage Calculator
Find the area of a room, a triangular section, or a circular space. See the result in your selected units, square feet, and square meters.
Area & Square Footage Calculator
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How to use this calculator
Calculate a triangle or circle
A triangle has area base × perpendicular height ÷ 2. A circle has area π × radius². If a circle has diameter 10 feet, enter a radius of 5 feet; its area is about 78.53981634 square feet.
Handle an irregular space
Divide an L-shaped room into non-overlapping rectangles. Calculate each rectangle separately and add the areas. Subtract excluded cutouts when appropriate. A single rectangle bounding the whole room will overstate the area if it includes empty corners.
Separate area from purchasing quantity
Area is a measurement, not a material order. Add any project-specific allowance for cuts or waste separately and check packaging coverage. This calculator does not determine property appraisal square footage, building-code compliance, or a professional measurement standard.
A LITTLE MORE CLARITY
Common questions
Why is a square foot not 0.3048 square meters?
The length conversion is squared: 1 ft² = 0.3048 × 0.3048 = 0.09290304 m².
What if I measured in feet and inches?
Convert each dimension into decimal feet first. For example, 12 feet 6 inches becomes 12.5 feet.
About this tool
Created by Marchelle Cook at Roof & Ratio. These calculations run in your browser; entered values are not uploaded or saved by the calculator. Report a calculation issue with an example so we can review it.
Guide updated October 23, 2026. Displayed decimal results may be rounded; exact fraction and integer results are identified in the answer.