Tile Calculator
Figure tile for a floor, wall or shower. Waste adjusts to your layout, thinset to your trowel size, and grout to the actual joint size.
How it's calculated
Each tile covers its own size plus one grout joint. The calculator divides your area by that and adds layout waste: 10% for a straight grid, 12% for offset, 15% for diagonal and 20% for herringbone.
Thinset coverage depends on the trowel, which depends on tile size. Grout is calculated from the actual joint volume: the length of joint per square foot, times joint width, times tile thickness.
Worked example
A 12 × 10 ft floor in 12 × 24" tile laid offset with 1/8" joints: 120 sq ft × 1.12 ÷ 2.02 sq ft per tile = 67 tiles, 3 bags of thinset with a 1/2" notch trowel, and about 7 lb of grout.
Field notes
- Dry-lay a row each direction before you spread thinset to find the best cut layout.
- Large-format tile (any side over 15") needs a flat floor, a large-notch trowel and back-buttering.
- Offset plank tile no more than 1/3 of its length to avoid lippage from tile bow.
- Keep at least one unopened box for future repairs.
Common questions
- How much extra tile should I buy?
- 10% for straight layouts, 15% for diagonal and up to 20% for herringbone or rooms with many cuts.
- How much grout do I need?
- It depends on tile size, joint width and depth. Small tiles with wide joints use far more. Use the calculator; a 25 lb bag often covers 100–300 sq ft.
- What size trowel for 12×24 tile?
- Usually a 1/2" × 1/2" square notch, with back-buttering, for full coverage.