Tile, Grout & Mortar: Calculators, Diagrams & Guides
4 calculators · 12 diagrams · 2 guides
Tile jobs are a chain of small quantities that each punish a bad guess: tiles per box with pattern waste, thinset bags by trowel notch, grout pounds that swing wildly with joint width and tile thickness, and the waterproofing behind wet walls that no one sees until it fails. The four calculators in this hub cover the chain — floor and wall tile counts, backsplash takeoffs with outlet cutouts, grout weight from the exact joint geometry, and mortar coverage by trowel size and tile format.
The diagrams hold the trade knowledge: layout starting lines that keep cut tiles balanced at the walls, lippage control on large-format tile, the wet-wall assembly from stud to surface, which trowel notch pairs with which tile size, and why big tile demands back-buttering and a ½-inch notch while mosaic runs happy on a ¼-inch V.
The math follows the TCNA Handbook and ANSI A108/A118 standards — the same documents inspectors and manufacturer warranties reference — including the ANSI A108.02 grout-joint minimums and mortar coverage requirements (80 percent dry areas, 95 percent wet). All four calculators are free with no signup, and each tool links to its full installation guide for the how, not just the how-much — layout, membrane, and grouting sequence included.
Tile, Grout & Mortar calculators
- Tile CalculatorCalculate tiles, thin-set, grout (TCNA formula), membrane, leveling clips & EJ171 movement joints for floor, wall or shower. Free, no signup.
- Backsplash Tile CalculatorInstantly calculate backsplash tiles, grout bags, thinset & trim for ceramic, glass, marble & mosaic. TCNA/ANSI formulas. Free, no signup needed.
- Grout CalculatorCalculate how much grout you need in bags, boxes, or epoxy units from your tile size, joint width, and area — TCNA/ANSI coverage formula. Free, no signup.
- Mortar / Thinset CalculatorPick the right ANSI mortar (A118.1/.4/.11/.15/.3 or A136.1 mastic) for substrate and tile, then get bag count by trowel notch. NTCA, TCNA, ANSI A108.
Guides & references
Tile, Grout & Mortar · 12 diagrams
- Tile, Grout & Mortar
How trowel notch size sets the mortar bed and the coverage per bag
A bigger notch lays a deeper bed for bigger tile — so it uses more mortar and covers fewer square feet per bag (¼″ square ≈ 80 sq ft/bag; ¾″ U-notch ≈ 30). Match the notch to the tile size.
- Tile, Grout & Mortar
Thinset contact coverage — why combed ridges must be collapsed (80% / 95% rule)
Combing the mortar isn’t the goal — contact under the tile is. Ridges left standing leave voids (<80%); sliding the tile to collapse them plus back-buttering gives the ≥95% contact ANSI requires for wet and large-format tile.
- Tile, Grout & Mortar
Which ANSI thinset class to use by substrate and exposure (A118.1 / .4 / .15 / .3 / mastic)
Substrate and exposure pick the class. The classic trap: over a sheet membrane use UNMODIFIED — modified mortar can’t cure sealed between two impervious layers. Mastic is interior-dry small wall tile only.
- Tile, Grout & Mortar
How tile layout pattern drives waste — straight ≈7%, diagonal & herringbone ≈15%
The layout pattern — not just the square footage — sets your waste factor: straight ≈7%, running bond ≈10%, diagonal 45° ≈15%, herringbone ≈15%+. Angled patterns throw away a cut at every wall.
- Tile, Grout & Mortar
Large-format tile offset limit — stagger ≤33%, not 50%, to avoid lippage
Any tile edge ≥15″ is large-format. Stagger it ≤33% of the tile length (not a 50% brick bond) so the joint stays off the slightly crowned center — otherwise you get lippage. Set with medium-bed mortar at 95% coverage.
- Tile, Grout & Mortar
What goes behind shower tile — cement board, waterproofing membrane, then tile
Tile and grout are not waterproof — the membrane behind them is. A shower wall is framing → cement board (never standard drywall) → A118.10 waterproofing membrane → thin-set at 95% coverage → tile.
- Tile, Grout & Mortar
Measuring a backsplash — width times the band height, minus only the big openings
Measure each run as width (ft) × band height (in) ÷ 12. The standard band is 18″ counter-to-cabinet. Deduct only large openings (≥1 sq ft); tile around outlets. Then add the pattern waste factor.
- Tile, Grout & Mortar
Grout joint width picks the grout — sanded for wide joints, unsanded for narrow
Joint width decides the grout: ≥1/8″ → sanded (the sand resists cracking in wide joints), under 1/8″ → unsanded (sand won’t pack a thin joint). Glass and cement tile → ALWAYS unsanded, because sand scratches glass.
- Tile, Grout & Mortar
Backsplash finish details — metal or bullnose at exposed edges, caulk (not grout) at the counter
Finish the exposed outer and top edges with a metal profile or bullnose, not a raw tile edge. Caulk (not grout) the countertop joint, inside corners, and cabinet edges — those are movement joints (TCNA EJ171). Grout only the flat field.
- Tile, Grout & Mortar
Tile size drives grout quantity — small tiles need far more grout than large ones
At the same joint width, small tiles use dramatically more grout than large ones: a 2×2 mosaic needs ~12× the grout of a 24×24 tile over the same area. Grout per sq ft = (L+W)/(L×W) × joint width × joint depth × 144.
- Tile, Grout & Mortar
Grout fills the joint full-depth — the joint is a channel of width × depth × length
Grout fills the joint full-depth (ANSI A108.10), not just the surface — so the grout in a joint is a channel: width × depth × length. Depth equals tile thickness, which is why a thick floor tile uses far more grout than a thin mosaic at the same joint width.
- Tile, Grout & Mortar
Unsanded, sanded, or epoxy grout — chosen by joint width, surface, and how it is sold
Joint width picks the grout: unsanded for 1/16″–1/8″ (and glass/polished stone), sanded for 1/8″–1/2″, epoxy for wet or chemical areas. Cementitious grout is sold by weight and sealed; epoxy is sold by the kit and never sealed.
Frequently Asked Questions
How much tile should I order beyond the room measurement?
Ten percent for straight layouts, 15 for diagonal or patterned installs, and consider rounding up a further box on natural stone where breakage and shade-matching matter. Ordering the buffer up front keeps every tile in one dye lot — a matched replacement box later is never guaranteed. The tile calculator converts area to boxes with the pattern factor applied.
How much thinset do I need per square foot?
It depends on the trowel, which depends on the tile: a ¼×¼ square notch covers roughly 60 to 70 sq ft per 50 lb bag, while the ½×½ notch large-format tile demands covers nearer 30 to 40. The mortar calculator pairs tile size to notch per TCNA guidance and outputs whole bags, including back-butter allowance for tile over 15 inches.
How do I know how much grout to buy?
Grout volume is geometry: (tile length + width) ÷ (length × width) × joint width × joint depth × density. Doubling the joint width doubles the grout; thicker tile deepens every joint. The grout calculator runs the formula from your exact tile and joint dimensions and outputs pounds, sized to the boxes grout is actually sold in.
What size grout joint should I use?
ANSI A108.02 sets the floor at 1/16 inch for rectified tile, with 3/16 the common floor-tile default and ⅛ typical on walls. The practical rule: the joint must absorb the tile’s size variation — calibrated rectified tile can run tight; handmade and natural stone need wider joints to keep lines reading straight over a full wall.
Do I need to waterproof behind shower tile?
Yes — tile and grout are not waterproof; the assembly behind them is what keeps the wall dry. Code and TCNA methods require a waterproof membrane (sheet or liquid-applied) over an appropriate backer board in wet areas. Cement board alone lets vapor through. The wet-wall assembly diagram in this hub shows the full stack from stud to tile face.