Enter the size of your floor, wall or backsplash and your tile size to see how many tiles and boxes to buy, plus grout and thinset.
Quick answers
Tiles needed = area ÷ the area of one tile plus its grout joint, then about 10% extra (Daltile). A 10 × 12 ft floor with 12 × 12 in tile and 1/8 in joints needs 130 tiles.
A 25 lb bag of sanded grout covers about 383 sq ft of 12 × 12 × 3/8 in tile with 1/8 in joints, but only 94 sq ft with 1/2 in joints (MAPEI Keracolor S chart).
A 50 lb bag of thinset covers about 75 to 90 sq ft with a 1/4 × 1/4 in square-notch trowel and 55 to 65 sq ft with a 1/4 × 3/8 in trowel (MAPEI Ultraflex 2).
How to use the tile calculator
Measure the floor or wall in feet. For L-shaped rooms, add the rectangles with the square footage calculator and enter the total.
Enter the tile's real size in inches, as printed on the box, and the grout joint you plan to use.
Add the square feet per box from the label to get a box count.
The formulas
Tiles = area (sq ft) × 144 ÷ ((tile length + joint) × (tile width + joint)), plus the extra, rounded up.
Grout volume = area × (tile length + tile width) ÷ (tile length × tile width) × joint width × tile thickness × 144 cubic inches. MAPEI's Keracolor S coverage chart works out to about 430 cubic inches per 25 lb bag in every row, so we divide by 17.2 to get pounds.
Thinset uses the low end of MAPEI Ultraflex 2's published coverage, so you are less likely to run short.
Worked example: a 10 × 12 ft bathroom floor
120 sq ft of 12 × 12 in tile, 3/8 in thick, with 1/8 in joints. Each tile plus joint covers 12.125 × 12.125 = 147 sq in, so 120 × 144 ÷ 147 = 117.5 tiles. With 10% extra, buy 130 tiles, or 9 boxes of 15 sq ft. Grout: about 8.6 lb, so one 10 lb bag or one 25 lb bag. Thinset: 132 sq ft ÷ 75 = 2 bags of 50 lb.
Tiles and grout per 100 sq ft
No extra added. Grout in pounds, sanded.
Tile
Joint
Tiles
Grout (lb)
3 × 6 in subway
1/16 in
776
8.2
6 × 6 in
1/8 in
384
8.7
12 × 12 in
1/8 in
98
6.5
12 × 24 in
1/8 in
50
4.9
24 × 24 in
1/8 in
25
3.3
Common questions
How many tiles do I need for 100 square feet?
With 12 × 12 in tile and 1/8 in joints, each tile plus its joint covers about 1.02 sq ft, so 100 sq ft takes 98 tiles. Add 10% for cuts and breakage and buy about 108. For 6 × 6 in tile with 1/8 in joints it is about 384 tiles before the extra.
How much extra tile should I buy?
Daltile recommends buying about 10% more than you measure. Diagonal and herringbone layouts produce more offcuts, so many installers order more for those. Keep a few spare tiles from the same lot for future repairs; colors can vary between production runs.
How much grout do I need?
It depends on joint width, tile size and tile thickness, because grout only fills the joints. Smaller tiles and wider joints use much more. The calculator uses the coverage chart in MAPEI's Keracolor S data sheet: about 430 cubic inches of joint per 25 lb bag.
What size trowel should I use for tile?
Pick the notch that gives full mortar contact. The industry standard (ANSI A108.5) calls for at least 80% contact in dry indoor areas and 95% in wet areas and outdoors. Larger tiles need a bigger notch. Press a tile in, lift it and check the back. The tile and mortar instructions list the notch sizes they approve.
Does the joint width change how many tiles I need?
Slightly. Each joint adds to the space a tile covers, so wider joints mean fewer tiles. With 12 in tile, a 1/8 in joint saves about 2% of tiles compared with butting them tight. With small mosaic tile the effect is much bigger.