Square Footage Calculator

Find the square footage of any room or area from its length and width, add a waste allowance for cuts, and estimate total material cost for flooring, tile, paint, or sod.

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How to Calculate Square Footage

Square footage is simply length multiplied by width, with both measurements in feet. A room that is 12 feet long and 10 feet wide is 12 × 10 = 120 square feet. If a measurement is in feet and inches, convert the inches to a decimal first (divide inches by 12), so 10 feet 6 inches becomes 10.5 feet.

Square Footage = Length (ft) × Width (ft)

Adding a Waste Allowance

For flooring, tile, and similar materials you should always buy more than the bare area to cover cuts, breakage, and pattern matching. A 10% overage is typical for straight-lay flooring and standard rooms; 15% is safer for diagonal tile, herringbone, busy patterns, or rooms with lots of corners and angles. This calculator adds your chosen percentage on top of the measured area so the material total reflects what you actually need to order.

Measuring Irregular or Multi-Room Spaces

For an L-shaped room or an open floor plan, split the space into rectangles, calculate each one separately, and add the results. Use the "number of identical areas" field when you have several rooms or sections of the same size. For round areas, multiply the radius by itself and then by 3.1416 (πr²).

From Square Feet to Material and Cost

Once you know the square footage plus waste, multiply by the price per square foot to estimate material cost. Flooring and tile are usually sold by the square foot or by the box (with a stated coverage), while paint is sold by the can with a coverage rating — one gallon typically covers about 350 to 400 square feet per coat.

Frequently Asked Questions

How do you calculate the square footage of a room?
Measure the length and width in feet and multiply them together. A 12 ft by 10 ft room is 120 square feet. For measurements in feet and inches, convert inches to a decimal by dividing by 12 first — 10 ft 6 in becomes 10.5 ft.
How much waste should I add for flooring or tile?
Add about 10% extra for standard straight-lay flooring and simple rooms, and 15% for diagonal layouts, herringbone or chevron patterns, large tiles, or rooms with many corners and angles. The extra covers cuts, breakage, and future repairs.
How do I find the square footage of an L-shaped room?
Divide the space into separate rectangles, calculate the square footage of each (length × width), and add them together. The same approach works for any irregular floor plan — break it into rectangles you can measure.
How many square feet does a gallon of paint cover?
One gallon of interior wall paint covers roughly 350 to 400 square feet per coat. Most walls need two coats, so divide your total wall square footage by about 350 and then double it to estimate gallons for full coverage.
How do I convert square feet to square yards or square meters?
Divide square feet by 9 to get square yards (carpet is often sold this way), or multiply square feet by 0.0929 to get square meters. So 120 sq ft is about 13.3 sq yards or 11.15 sq meters.