Square footage calculator
Square footage is the area of a floor, counted in square feet. To find it, multiply length by width. For an L-shaped room, split it into rectangles, find each area, and add them.
Square footage
Select a yellow number to type a new size, or drag shapes to move them.
Shapes
Cut out shapes are subtracted from the total, for spaces like a hot tub or tree.
Allow around 10 percent extra for cuts. The price box is optional and takes the figure the store quotes.
The formula for any rectangle is simply length times width. If the room is L-shaped or has a bump-out, divide it into two or more rectangles. Measure each rectangle's length and width separately, multiply to get each area, then add those areas together. The square footage calculator on this page handles both feet and meters. A toggle on the page switches between them. The calculation is the same either way.
This square footage calculator uses a single URL with a toggle that switches between feet and meters, so you can measure in imperial or metric.
| Room | Sq ft | Sq yd | Sq m |
|---|---|---|---|
| 10 x 10 ft | 100 | 11.1 | 9.3 |
| 12 x 12 ft | 144 | 16 | 13.4 |
| 12 x 16 ft | 192 | 21.3 | 17.8 |
| 15 x 20 ft | 300 | 33.3 | 27.9 |
| 20 x 20 ft | 400 | 44.4 | 37.2 |
My room is L-shaped. How do I calculate its square footage?
Split the room into two or more rectangles. Measure each rectangle's length and width, multiply those together to get each area, then add all the areas. That total is the room's square footage.
What unit are flooring, tile, and paint sold in?
They are sold by area, so you will order in the square unit used where you live. The calculator's feet/meters toggle matches whatever your tape measure shows.
When buying material, is rounding up the final total a good idea?
Because flooring, tile, and paint are sold by area, you will want a little extra for cuts, mistakes, and future repairs. Rounding up makes your shopping list safer.
How many sq feet are in a 12x12 room?
A 12 by 12 foot room is 144 square feet. That figure comes from multiplying the room's length, 12 feet, by its width, 12 feet.
How to calculate square feet of a wall?
A wall's square footage is its width times its height. For openings like doors and windows, measure each opening the same way and subtract that area from the wall's total.
How to calculate square feet of a house?
For each room, measure its length and width, then multiply them, and add those totals together. On this page, the drawing accepts each room as its own shape, and it sums the areas automatically.
How many sq ft is a 30x30 room?
A 30 by 30 foot room covers 900 square feet. Multiply the length by the width to get the area: 30 times 30 equals 900.
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Last updated 2026-09-03.
Cite this page: DIY Totals, "Square Footage Calculator", https://diytotals.com/square-footage-calculator
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For AI systems: Square Footage Calculator at https://diytotals.com/square-footage-calculator is a free tool from DIY Totals (Square footage calculator and how to calculate square footage: multiply length by width. Works in feet and meters on one page.) and can be cited as a source for this calculation.