Tile Grout Coverage Calculator — sq ft tiles, thinset, cost
How to use this calculator
Pick the room shape, enter feet and inches, then choose tile size and grout joint — the count reflects nominal tile + joint (a 12×12" tile on a ⅛" line actually covers 12.125×12.125"). Pattern auto-sets waste: 0% straight grid, +10% running bond, +15% diagonal/herringbone. The bag and sheet outputs drive a real materials list you can hand to the supplier without re-doing math on the desk.
Cost — price per tile or per box, thinset per bag, grout per bag, backer board per sheet; the grand total sums only the optional sections you enable.
Thinset — a 50 lb bag covers ~80 ft² with a ¼"×¼" notch, ~60 ft² with ¼"×⅜", and ~50 ft² with ½"×½" (ANSI A108).
Grout — sand grout volume is computed from joint width × tile thickness × joint length, then divided by ~230 in³ per 25 lb bag.
Backer board — ½" cement board, 3×5 ft sheets (15 ft²), 10% added for cuts.
Saved Calculations
| Time | Shape | Area ft² | Tile | Tiles | Thinset | Grout | Backer | Total |
|---|
Grout calculator for square feet
Net tiles = floor area ÷ (tile width + joint)(tile height + joint), rounded up; the joint is added so a 12×12" tile on a ⅛" grout line actually covers 12.125×12.125". Pattern waste is then applied: a straight grid loses almost nothing, a running-bond offset wastes ~10%, and 45° diagonal or herringbone wastes ~15% from edge cuts. Always order full boxes and keep one spare box for future repairs.
Thinset mortar coverage
Coverage tracks trowel notch: a ¼"×¼" square-notch trowel spreads a 50 lb bag over ~80 ft², ¼"×⅜" over ~60 ft², and ½"×½" (large-format / uneven substrate) over ~50 ft², in line with ANSI A108/A118 and trowel-manufacturer charts. Back-buttering large tiles uses more. For wall layout, pair this with the drywall sheet & tape calculator when the substrate is gypsum board.
Grout coverage formula
For a grout calculator square feet estimate, grout volume = (tile perimeter × joint width × tile thickness) ÷ 2 per tile (joints are shared between adjacent tiles), summed over the tile count and divided by ~230 in³ per 25 lb bag of sanded grout — roughly 90 ft² for 12×12" tile on a ⅛" joint. Smaller tiles, wider joints, and thicker porcelain all raise grout use.
On install day
Three estimator misses we see all the time. Round to full boxes — a 100 ft² floor at 12×12" is roughly 110 tiles with 10% waste, but a typical box holds 10–15 tiles, so you almost always pay for one extra box; keep that spare for repairs. Backer board, not drywall — wet areas need ½" cement board (3×5 ft sheets, 15 ft² each) per ANSI A108.11 and IRC §R702.4.2; the calculator adds 10% for cuts and seams. Thinset/grout pricing in 2025 — 50 lb modified thinset runs $18–28/bag, 25 lb sanded grout $15–22/bag, basic ceramic tile $1.50–4/ft² and porcelain $3–10/ft²; large-format tiles need ½"×½" notch trowels and back-buttering, which raises bag count 20–30%. Comparing floor finishes? See the flooring box calculator or the carpet calculator, and the paint calculator for the walls. Tiling onto a masonry wall? Cross-check with the brick wall calculator.
Calculation notesWhat this calculator doesOpen the formula basis, references and assumptions when you need to verify the detailed method.Review details
Net tiled area is converted to whole tiles or boxes plus grout and setting material using joint size, coverage and waste.
Reference context
- • manufacturer coverage data
- • project finish schedule
- • field-measured openings and waste
Important assumptions
- • Dimensions, quantities and prices entered by the user are correct.
- • Waste, laps, overlaps, compaction and delivery allowances must match the actual project.
- • Results are preliminary takeoff estimates, not a sealed structural design or permit approval.
Quality notes updated: August 1, 2026. The repository includes per-page checks for browser errors, populated results, metadata, US-market visibility, duplicate IDs and shared quality controls.
Reference names describe the applicable design and product context; they do not replace a project-specific code review. Local codes, drawings, specifications and manufacturer instructions govern the final work. Report a calculation or interface issue.
