Square Footage Calculator
Work out the square footage of an area from its length and width in feet and inches, across one or more identical areas, with an optional waste allowance and material cost. Calculates in your browser.
Total square footage
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Show the math
Inches convert to feet, then length times width gives the area:
square footage = length (ft) × width (ft)
with waste = total × (1 + waste%)
For flooring, tile, or paint, buy to the area with waste added, about 10% for straight layouts, 15–20% for diagonal patterns. Split an L-shaped room into rectangles and add them. All math runs locally in your browser.
What this does
A square footage calculator works out the floor area of a space from its length and width in feet and inches. Multiply by a count of identical areas, add a waste allowance, and enter a price per square foot to estimate material cost.
How to use it
- Enter the length and width in feet and inches.
- Set how many identical areas you have.
- Add a waste allowance if you are buying material.
- Read the square footage and estimated cost.
How it works
Inches are converted to feet (inches ÷ 12) before multiplying, so the area comes out in square feet. The waste allowance and price per square foot are applied to the total area to estimate what to buy and spend.
square footage = length (ft) × width (ft)
Understanding your result
For flooring, tile, or paint the figure that matters is the area with waste added, about 10 percent for straight layouts, more for diagonal patterns or rooms with many cuts. Break an L-shaped room into rectangles and add them, and measure at the widest points so you do not come up short.
Example
An area 12 ft 6 in by 10 ft is 125 sq ft; with 10% waste you would buy material for about 138 sq ft.
Sources & methodology
Last updated .
Frequently asked questions
How do I calculate square footage?
Multiply length by width, both in feet. For feet-and-inches measurements, convert inches to feet first (divide by 12), then multiply.
How do I handle an L-shaped or irregular room?
Split it into rectangles, find the square footage of each, and add them together. Enter each rectangle as a separate area and sum the results.
How much waste should I add?
About 10% for straight flooring or tile layouts, and 15–20% for diagonal patterns or rooms with lots of cuts and angles.
Do you store my numbers?
No. Everything is calculated locally in your browser.
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