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20x20 is 400 square feet
A 20 × 20 ft room is 400 square feet. Add closets, bump-outs or cut-outs below to measure your exact space.
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How many square feet is 20x20?
Multiply length by width: 20 × 20 = 400 square feet. That is 44.4 square yards, 37.2 square metres, or 0.0092 acres.
Flooring for a 20x20 room
Order about 10% extra for cuts and waste: 440 square feet for straight-laid flooring or tile, and about 15% (460 sq ft) for diagonal or herringbone patterns. The tile calculator turns this into boxes and grout.
Paint for a 20x20 room
With 8 ft ceilings the walls total about 640 square feet before doors and windows. Two coats at about 350 sq ft per gallon is roughly 4 gallons. The ceiling adds another 400 square feet.
How to calculate square footage
For a rectangle, multiply length by width in feet. A 12 × 10 ft room is 120 square feet. For a room that is not a plain rectangle, break it into rectangles, triangles or circles, find each area, then add them up. Subtract anything you are leaving out, such as a closet or fireplace.
Formulas for each shape
- Rectangle: length × width
- Triangle: base × height ÷ 2
- Circle: π × (diameter ÷ 2)²
- Trapezoid: (base 1 + base 2) ÷ 2 × height
What to do with the number
Square footage is the starting point for flooring, paint, sod and cost estimates. Once you have it, size the job with the tile calculator, the concrete calculator or the gravel calculator.
Square footage of common room sizes
Frequently asked questions
How many square feet is a 20x20 room?
400 square feet (20 × 20).
What is 20x20 in square feet?
20x20 in square feet is 400 sq ft. That equals 44.4 square yards or 37.2 square metres.
How much flooring do I need for a 20x20 room?
About 440 square feet with 10% waste, or 460 for diagonal patterns.
How do I calculate the square footage of an irregular or L-shaped room?
Split it into simple shapes, measure each one, and add the areas. An L-shaped room is two rectangles. Add each part as its own section in the calculator and the total updates.
How much extra should I order for flooring, tile or paint?
Most guides suggest 5 to 10 percent for waste, and 10 to 15 percent for diagonal patterns or lots of cuts. Enter the percentage in the waste box to see the amount to buy.
Is my data stored?
No. Everything is calculated in your browser. Nothing is uploaded or saved.