Tile Calculator
Enter the area to tile, your tile size and grout joint, and the coverage or tile count printed on the box.
How it works
Area = length × width − any area left out. Each tile covers (tile length + joint) × (tile width + joint) ÷ 144 sq ft. Tiles = area × (1 + allowance) ÷ area per tile, rounded up. Boxes = tiles ÷ tiles per box, or area with allowance ÷ box coverage, rounded up. Metric inputs are converted with NIST factors (1 ft = 0.3048 m, 1 in = 25.4 mm).
Worked example: A 10 × 12 ft floor is 120 sq ft; with 10% that is 132 sq ft. A 12 × 12 in tile with a 1/8 in joint covers 12.125 × 12.125 ÷ 144 = 1.021 sq ft, so 132 ÷ 1.021 = 129.3, rounded up to 130 tiles, or 9 boxes of 15 sq ft.
Assumptions
- Flat, rectangular area. For L-shaped rooms, add the rectangles with the square footage calculator and enter the total as one length × width (for example 150 × 1).
- Waste default 10%. Daltile recommends buying about 10% more tile than you expect to need as "attic stock" for future repairs from the same dye lot. Diagonal and herringbone layouts, small rooms and many cuts can need more; ask your tile supplier.
- Grout joint default 1/8 in is an example, not a standard. TCNA says there is no specific standard for joint size; the project owner chooses it, and follow the tile maker's guidance.
- Grout, thinset, backer board and trim are not included.
- This is a quantity estimate only. Follow the product's installation instructions and check local codes.
Frequently asked questions
How many tiles do I need for 100 square feet?
With 12 × 12 in tiles and no joint, 100 tiles before any allowance. With a 1/8 in joint, each tile covers 1.021 sq ft, so about 98 tiles, or 108 with a 10% allowance.
How much extra tile should I buy?
Daltile recommends about 10% extra as attic stock for repairs, because later production runs can vary slightly. Complex layouts and many cuts can need more.
Does the grout joint change the number of tiles?
Slightly. Each tile covers its own face plus one joint width in each direction, so wider joints mean a few fewer tiles. TCNA notes joints of 1/8 in and larger generally use sanded grout.
Related calculators
Sources
Formulas and reference values are from these sources. Page content last updated 2026-10-19.