Measurement
Calculate floor and wall tile square footage, full retail boxes to purchase, cutting waste allowance, and grout bag requirements.
Enter room or wall length and width, select tile dimensions, and enter tiles per box. The calculator figures net area, required tiles with cutting allowance, full boxes to purchase, and estimated grout.
Calculation and worked example reviewed 2026-11-14. See our calculation methodology.
132 tiles total (120 base + 10% cutting allowance). 14 full boxes provide 140 tiles (8 attic stock spares).
Grout requirement: ~2 bags (25 lb dry grout, 1/8" joints) · ~120 sq ft thin-set mortar coverage.
Formula and example
This estimator converts your entered jobsite inputs (room or wall length, room or wall width, tile dimensions, tiles per box, grout joint width, waste & cutting allowance) into consistent US trade units, computes the exact geometric baseline first, and then applies any selected waste or order allowance so you can verify both numbers before purchasing materials.
where:
Net area = length × width; tile area = (length in × width in) ÷ 144; base tiles = net area ÷ tile area; order tiles = ceil(base tiles × (1 + waste% ÷ 100)); order sq ft = order tiles × tile area; boxes = ceil(order tiles ÷ tiles per box); grout bags (25 lb) = ceil(net area ÷ bag coverage).
A 12 ft × 10 ft kitchen floor (120 sq ft) with standard 12 × 12 in tiles, 10 tiles/box, and 10% waste requires 132 tiles. At 10 tiles per box, order 14 full boxes (140 tiles total) and 2 bags (25 lb each) of grout for 1/8-inch joints.
Estimates based on 10 tiles/box and 1/8 in grout joints for typical residential room sizes.
| Room / Area | Net Area | 12 × 12 Tiles (Boxes) | 25-lb Grout Bags |
|---|---|---|---|
| 5 ft × 8 ft bathroom | 40 sq ft | 44 tiles (5 boxes) | 1 bag |
| 8 ft × 10 ft laundry / bath | 80 sq ft | 88 tiles (9 boxes) | 1 bag |
| 10 ft × 12 ft kitchen | 120 sq ft | 132 tiles (14 boxes) | 2 bags |
| 12 ft × 15 ft dining room | 180 sq ft | 198 tiles (20 boxes) | 2 bags |
| 16 ft × 20 ft open living | 320 sq ft | 352 tiles (36 boxes) | 4 bags |
Assumes rectangular floor or wall with uniform tile size. Mosaic sheets on mesh backing, complex multi-size pattern layouts (e.g. Versailles pattern), and heavy diagonal/herringbone cuts require customized layout planning and 15% to 20% waste allowance.
A standard straight grid (stack bond) or 1/3 offset running bond requires a 10% waste factor for edge cuts, doorway transitions, and minor breakage. Diagonal (45°) and herringbone patterns generate significantly more perimeter triangular offcuts and require 15% to 20% waste.
Most tile suppliers, home improvement centers, and distributors sell ceramic and porcelain tile by sealed full cartons to protect against shipping breakage and to guarantee that all tiles in your order originate from the same manufacturing dye lot and caliber sizing.
For standard 12 × 12 inch floor tiles with 1/8-inch grout joints, one 25-pound bag of polymer-modified dry grout typically covers roughly 100 square feet. Smaller tiles like 3 × 6 subway tiles have many more linear feet of joints per square foot and require about twice as much grout per unit area.
Attic stock is an extra 1 to 2 unopened boxes of matching tile stored in your garage or attic. Because tile dye lots, sheen, and dimensions shift between manufacturing runs, attic stock guarantees an identical match if you ever need to replace a cracked tile or repair plumbing behind a wall.
Method references: TCNA: Tile Council of North America installation guidelines