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30x40 is 1200 square feet
A 30 × 40 ft space is 1200 square feet. Add closets, bump-outs or cut-outs below to measure your exact space.
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How many square feet is 30x40?
Multiply length by width: 30 × 40 = 1200 square feet. That is 133.3 square yards, 111.5 square metres, or 0.0275 acres.
Flooring for a 30x40 space
Order about 10% extra for cuts and waste: 1,320 square feet for straight-laid flooring or tile, and about 15% (1,380 sq ft) for diagonal or herringbone patterns. The tile calculator turns this into boxes and grout.
Paint for a 30x40 space
With 8 ft ceilings the walls total about 1120 square feet before doors and windows. Two coats at about 350 sq ft per gallon is roughly 7 gallons. The ceiling adds another 1200 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 30x40 room?
1200 square feet (30 × 40).
What is 30x40 in square feet?
30x40 in square feet is 1200 sq ft. That equals 133.3 square yards or 111.5 square metres.
How much flooring do I need for a 30x40 room?
About 1,320 square feet with 10% waste, or 1,380 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.