Tile Calculator
The short answer for 100 sq ft of 12×12 tile: 110 tiles, 2 bags of thinset, 1 bag of grout and 7 backer-board sheets. Enter your area and tile below for your number.
Materials list
| Item | Quantity |
|---|---|
| Tile — 12 x 12 in (incl. 10% waste) | 110 tiles |
| Thinset — CUSTOM VersaBond Professional Thin-Set Mortar (TDS-119), 50 lb bags (1/4 x 1/4 x 1/4 in square-notch) | 2 bags |
| Grout — MAPEI Keracolor S Premium Sanded Grout (polymer-modified, ANSI A118.6), 25 lb bags (chart row 12 x 12 x 3/8) | 1 bags |
| Backer board — 3 × 5 ft sheet (15 sq ft) | 7 sheets |
How it works
Tile count is the area divided by the tile's face area, plus your waste allowance, rounded up. Thinset bags use the manufacturer's coverage chart for the default product (CUSTOM VersaBond Professional Thin-Set Mortar (TDS-119)) at the low end of its stated range. Grout uses MAPEI's published coverage grids — the exact chart row when your tile size and joint width are listed; when they are not (MAPEI lists no 12×24 row), the figure is scaled from the nearest listed row and the result is plainly labelled an estimate. Backer board rounds up to whole sheets.
Sources: Manufacturer technical data sheets: CUSTOM VersaBond TDS-119; MAPEI Kerabond TDS (ed. 2026-09-23), Keracolor S TDS (ed. 2026-02-26), Keracolor U TDS (ed. 2021-09-10); LATICRETE 254 Platinum DS-677-0621; TEC Super Flex DS392/393; USG Durock sell sheet CB319271; tile sizes from Why Tile (TCNA). Full evidence: research-data/tile.md Retrieved 2026-10-24.
Questions
How much thinset do I need for 100 sq ft of tile?
2 bags (50 lb) of CUSTOM VersaBond Professional Thin-Set Mortar (TDS-119) with a 1/4 x 1/4 x 1/4 in square-notch trowel. CUSTOM's TDS-119 chart puts that trowel at 90–100 sq ft per bag; this calculator plans on the low end so you do not run short mid-job.
How much grout for 12×12 tile with 1/8 in joints?
One 25 lb bag of MAPEI Keracolor S covers 383 sq ft on 12×12 tile at a 1/8 in joint (MAPEI Keracolor S technical data sheet, row 12 x 12 x 3/8) — so a 100 sq ft floor needs 1 bag.
Why does the calculator call my grout figure an estimate?
MAPEI's published grout charts do not list every tile size — there is no 12×24 row, for example. For an unlisted size the calculator scales from the nearest listed row using grout-volume proportions and labels the result an estimate, rather than pretending the chart says something it does not.
What size backer board should I buy?
Cement backer board comes in 3×5 ft (15 sq ft) and 4×8 ft (32 sq ft) sheets — USG Durock lists 1/4 in and 1/2 in in 3×5, and 1/2 in and 5/8 in in 4×8. A 100 sq ft floor takes 7 of the 3×5 sheets.