Square Footage Calculator
How many square feet are in that room, hallway, patio, or oddly shaped space? A tape measure and a little geometry will get you there. Enter up to three sections, and I’ll add them together without making you reach for scratch paper.
Then you can carry the result straight into our flooring, paint or concrete calculators. There’s also a printable picture lesson if you’d like to see how the math works.
Let’s measure the space
Break L-shaped rooms into rectangles that don’t overlap. Use a triangle for a true triangular corner. Leave both measurements at zero to skip an optional section.
Two shapes, two easy formulas
Example: A 12 × 10 ft rectangle plus an 8 × 6 ft triangle, minus a 2 × 5 ft uncovered area, is 120 + 24 − 10 = 134 square feet.
Square feet measure AREA, not distance. A square yard is 9 square feet. If you’re converting to material amounts, add any cutting waste in the flooring or paint tool instead of hiding it in your room measurement.
How to measure a room with corners and alcoves
A simple rectangular bedroom is easy: measure one wall, then the wall at a right angle to it. Multiply the two measurements. If you have an L-shaped room, imagine drawing a straight line that splits it into two rectangles. Measure each rectangle separately and add the answers.
Three tips make your answer more trustworthy: measure at the floor when estimating flooring, keep all dimensions in feet, and watch for sections that overlap. If you count the same corner twice, the result will be too large.
How do I measure a triangular space?
Multiply the triangle’s base by its perpendicular height and divide by two. The slanted side is not necessarily the height. For complicated angles and curved walls, sketch the room or take more measurements rather than pretending a rectangle fits.
What do square feet tell you when you’re shopping?
Square footage is the starting point, not the whole shopping list. Flooring is sold in boxes, often with cutting waste. Paint needs wall area and the number of coats, which are different from floor area. Concrete needs a third dimension, thickness, to get cubic feet. We keep those steps in their own tools so the units don’t get mixed up.
Once you have the area, try the Flooring Boxes Calculator, the Paint Calculator or the Concrete Calculator. Each one adds the project-specific details and explains what you’d actually need to buy.
How many square feet are in a square yard?
There are 9 square feet in one square yard because a yard is 3 feet long and 3 feet wide. Don’t divide by 3 when converting area; divide by 9.
Is this the same as an online floor plan?
No. It adds measurements you enter. It doesn’t measure your property, know your walls, or replace a floor plan. Check real dimensions before buying materials.
A better measuring kit?
If you’re measuring several rooms, a reliable tape measure or a laser distance measure can make the job easier. Neither replaces checking your measurements twice, especially around trim and corners.
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As an Amazon Associate I earn from qualifying purchases. The shopping link is optional and opens an Amazon search, not a verified product recommendation. This calculator is free.