Tile Calculator
This tile calculator estimates how many tiles and boxes a floor, wall, or backsplash needs from room size, tile size, grout joint, and waste, plus an optional cost.
How to use
- Choose imperial (feet and inches) or metric (meters and centimeters). Add each rectangular section, or enter the total area. Split an L-shape into rectangles and leave out cabinets or tubs you will not tile under.
- Enter tile length and width, and the grout joint. The default joint is 1/8 in (0.125), or 3 mm in metric.
- Set the waste percent. Use 10% for a straight layout, 15% for diagonal, and 20% for herringbone.
- Optionally enter tiles per box or coverage per box, and a price per tile or per box. Read the tile count, boxes, and cost.
Formula
Area is length × width, summed across sections, or the area you type. Each tile covers (tile length + one grout joint) × (tile width + one grout joint). Tiles before waste = area ÷ that coverage. Tiles with waste = that count × (1 + waste ÷ 100), rounded up to a whole tile. Boxes are tiles with waste ÷ tiles per box, or area with waste ÷ coverage per box, also rounded up. Cost is the price per tile × tiles with waste, or the price per box × boxes.
Example. A 10 × 12 ft floor is 120 sq ft. A 12 × 12 in tile with a 1/8 in joint covers 1.020942 sq ft, so the floor needs 117.54 tiles before waste. At 10% waste that is 129.29 tiles, which rounds up to 130. With no grout joint the same floor is 120 tiles, or 132 after 10% waste.
Example. Two sections, 8 × 10 ft and 4 × 5 ft, are 100 sq ft. The same 12 × 12 in tile and 1/8 in joint need 97.95 tiles before waste and 108 tiles with 10% waste.
Example. 130 tiles at 10 per box is 13 boxes. At $4.50 a tile, those 130 tiles cost $585.00.
Frequently asked questions
How do I calculate how many tiles I need?
Divide the area to cover by the area of one tile including its grout joint, then add a waste allowance. A 10 x 12 ft floor (120 sq ft) with 12 x 12 in tiles needs 120 tiles before waste, about 132 with 10% waste.
How much extra tile should I buy?
Plan on about 10% extra for straight layouts and 15-20% for diagonal, herringbone, or rooms with many cuts. Keep a few spare tiles for future repairs.
Does grout width change the tile count?
Slightly. Each tile effectively covers its own size plus one joint width, so wider joints mean a few fewer tiles.
How do I measure an L-shaped room?
Split it into rectangles, find each area, and add them. Subtract fixed cabinets or tubs you will not tile under.
How many boxes of tile do I need?
Divide the total tiles (with waste) by tiles per box, or total square feet by square feet per box, and always round up to a whole box.
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