How to Calculate How Much Tile You Need for a Room
Before you begin a tiling project, it's important to have enough tiles on hand to finish the job. If you run out before you're finished, you may find that the supplier has run out of the tiles you're using or that the ones in stock are slightly different from yours.
Calculating your tile requirements isn't complicated  all it takes are a few careful measurements and some simple math. If math isn't your forte, you can always make use of one the online calculators available on the websites of tile suppliers and manufacturers.

Measure the length and width, or height and width, of the floor or walls you're going to tile. Take all measurements in inches. Include the depth of the sides of niches for showers. Divide irregular shapes, such as walls that wrap around cabinets or turn corners, into smaller rectangles and measure the length and width of each rectangle.

Calculate the area of each rectangle you measured by multiplying the length and width of the measurement. Add the areas of all the rectangles to determine the total area you need to tile. This number is in square inches.

Multiply the length and width of the tile to determine its area. For example, a 4inch by 4inch tile is 16 square inches.

Divide the area of one tile  in square inches  into the total you just calculated to determine the number of tiles you need. For example, if you're tiling a 10by10foot wall  120 by 120 inches  and using 4by4inch tiles, divide 16 square inches into 14,400 square inches to find you need 900 tiles.

Convert the area you measured to square feet, if buying your tile by the box, by dividing by 144 to determine the number of boxes you need. Alternatively, measure in feet to begin with. The coverage of each box is marked on its front in square feet. For example, say the area of your 10by10foot wall is 100 square feet. If each box of tiles covers 20 square feet, you need five boxes to tile it.

Include an overage in your calculations. If you plan to have the tiles professionally installed, add 5 percent, but if you plan to do it yourself, and you aren't experienced, it's better to add 10 percent. If the area you're tiling is irregularly shaped, requiring multiple angled cuts, add 15 percent.
Tip
If you're tiling a triangular wall or floor, measure the distance from the triangle’s apex to its base, then measure the length of the base. Multiply these measurements together and divide by 2 to determine the area. A good rule of thumb is to plan to have one box of tiles left over after you've finished the job to store in the basement for the future. The extra tiles come in handy when a tile breaks or must otherwise be replaced.
The Drip Cap
 Before you begin a tiling project, it's important to have enough tiles on hand to finish the job.
 If you run out before you're finished, you may find that the supplier has run out of the tiles you're using or that the ones in stock are slightly different from yours.
 Add the areas of all the rectangles to determine the total area you need to tile.
 This number is in square inches.
 For example, say the area of your 10by10foot wall is 100 square feet.
References
Resources
Writer Bio
Chris Deziel has a bachelor's degree in physics and a master's degree in humanities. Besides having an abiding interest in popular science, Deziel has been active in the building and home design trades since 1975. As a landscape builder, he helped establish two gardening companies.
Photo Credits
 kadmy/iStock/Getty Images
 kadmy/iStock/Getty Images
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