What the tile calculators cover
Tile quantities are counted layer by layer. The count pages start from tile size and area with a waste allowance that follows the lay pattern: the diagonal page counts the cut at every perimeter position, the mosaic page counts sheets and the length of joint that small pieces carry, and the stair page counts treads, risers and nosings. The bed pages count adhesive from the trowel notch and grout from the joint geometry. The fixing pages count spacers, levelling clips and edge profiles, the substrate pages count backer board with its screws and tape and a crack isolation membrane, and the wet-room pages set out the fall to a drain and the tanking.
How the answers are worked out
A tile count is the area divided by the area one tile covers, plus a waste allowance, rounded up. The floor and wall tile page cites the TCNA Handbook and BS 5385, which give a lower allowance for a straight lay and a higher one for a diagonal or herringbone pattern, and it says box coverage varies by format and must come from the supplier. The diagonal page adds the waste from a triangular cut at each perimeter tile position, each wasting roughly half a tile's area. The mosaic page uses a lower allowance, because a mesh-backed sheet is cut between the tesserae with a knife and the offcut stays usable, and it counts the far greater length of joint that small pieces carry.
The adhesive pages work from the trowel notch. A square-notch trowel leaves ridges that cover roughly half the surface at full notch depth, so the mean bed is about half the notch, and the rates sit on ARDEX's data sheet line and a little above CUSTOM's VersaBond sheet, to err toward a spare bag. Back-buttering and solid-bed work apply adhesive twice or fill the ridges, so the method is a multiplier on the combed figure. The thinset page states that TCNA requires eighty per cent mortar coverage for dry interior work and ninety-five per cent for wet areas and exteriors.
Grout is derived and not tabulated. Tiles on a grid form modules of length plus joint by width plus joint, the joint is the share of the surface the tiles do not cover, and joint volume is that share times the area times the joint depth; the page checks the result against the consumption formula printed on cementitious grout packaging, which reads within a couple of per cent of it at common tile sizes. The weight page turns a joint volume into mass by the density of the grout, and the quarry tile page counts the wider joints of chemical-resistant grout as joint length times width times depth.
In a wet room the tanking page doubles the area before dividing by the coverage rate, because liquid tanking is specified in two coats with the second at right angles to the first and every published rate is per coat. It counts reinforcing tape at each internal junction and a collar at each pipe separately, since those are the junctions that split first. The fall page finds the screed volume for a point drain from the floor area times the depth at the drain plus two-thirds of the drop, and for a one-way fall from the depth plus half the drop.
Units and documents by market
The market setting chooses the system the answers appear in: square feet, pounds and inches for the United States, square metres and kilograms for the other three markets, each answer restated in the other system. The adhesive pages quote data sheets from both: a US maker's rate in square feet per bag and an ARDEX rate in kilograms of powder per square metre per millimetre of bed. The table shows which documents the calculators cite for each market.
| Market | Ordered by | Measured as | Worth knowing |
|---|---|---|---|
| United States | Boxes of tile, with adhesive in bags rated in square feet at a notch and backer board by the sheet | TCNA Handbook for waste, mortar coverage and backer board fastening; a CUSTOM Building Products data sheet for adhesive coverage | The TCNA requirement for mortar coverage is stated on the thinset page for dry interior and for wet areas. |
| United Kingdom | Boxes of tile, with adhesive in bags rated by kilograms of powder per square metre per millimetre of bed | BS 5385 for waste, cited with the TCNA Handbook on the floor tile page; ARDEX data sheets for adhesive rates | The adhesive rates sit on ARDEX data sheets, which state them in metric units. |
| Australia | Metric answers, with the same box and bag counts | Few pages here cite an Australian document: read their results against the code your state adopts | The site names the NCC as this market's reference. |
| Canada | Metric answers, metric first, with the same box and bag counts | Few pages here cite a Canadian document: the site names NBC 2020 as this market's reference | Provincial and municipal amendments govern over any model code, as the site's own market note says. |
Allowance, boxes and whole pieces
Counts round up because tiles are bought by the box, sheets whole and trim by the stock length. The edge profile page adds a waste allowance to the exposed edge length, the stair page counts nosings as the number of steps a stock length yields and not the total length divided by it, and the stair page carries a higher allowance than a floor of the same area because every tread and riser is a cut piece. The levelling clip page counts from joint length, since each tile contributes its length plus its width of shared joint, and counts wedges separately because wedges are withdrawn and reused while clips snap off in the adhesive.
The order the layers go on
The groups run from the surface down to the bed and back up. Count the tiles first, because the count sets the number of spacers, clips and the grout. Then the bed: adhesive from the notch the tile size asks for, and grout from the joint. Then the substrate: backer board fixed at the spacing the manufacturer and the TCNA Handbook give, with tape in the joints, and a crack isolation membrane where one is used. In a wet room the falls and the tanking come before any of it is laid.
What the calculators leave to others
Every figure that belongs to a product is an input from its data sheet: the box coverage, the bag coverage at a notch, the roll coverage of a membrane and the density of a grout. The grout page gives the joint volume, and the tile and grout page gives only a rough bag figure from the area. Tanking primer is required on absorbent substrates and commonly omitted on cement-based backer board, and the manufacturer's sheet governs which applies.
Which calculator for which job
Every tile calculator on the site, grouped by what it does for the material, with the reason it is here. Open the one that matches the question in front of you; each restates its answer in both unit systems.
Count the tiles
Tiles and boxes from an area, with the waste that a pattern, a diagonal lay, a mosaic sheet or a stair needs.
| Calculator | What it does for tile |
|---|---|
| Floor & Wall Tile Calculator | Tiles and boxes for a floor or wall, with the waste factor the lay pattern needs. |
| Tile Layout Calculator | The tiles an area takes from the tile size, with a waste factor. |
| Diagonal Tile Layout 45° Corner Cut Waste Calculator | The extra waste from the triangular cut at every perimeter position of a diagonal lay. |
| Mosaic Sheet Calculator | Sheets and boxes of mosaic, with the lower waste of a mesh-backed sheet and the joint length of small pieces. |
| Tiled Stair Calculator | Tile for the treads and risers of a flight, the nosings in whole stock lengths and the piece count. |
Adhesive, grout and the bed
The adhesive from the trowel notch, and the grout from the joint geometry, by volume, by weight and in bags.
| Calculator | What it does for tile |
|---|---|
| Thinset & Tile Adhesive Calculator | The adhesive a job takes from the trowel notch, which sets the coverage. |
| Tile Adhesive Calculator | Adhesive from the notch size and the bedding method, and the bags that makes. |
| Grout Calculator | The grout a floor or wall takes from the tile size and the joint width and depth, by weight and in bags. |
| Tile & Grout Calculator | The tiles a surface takes, with a rough grout bag figure from the area alone. |
| Grout Weight Consumption Calculator | A joint volume turned into the mass of grout, for buying in bulk. |
| Quarry Tile Acid-Resistant Grout Joint Volume Calculator | The chemical-resistant grout volume for the wider joints of quarry tile. |
Spacers, levelling and edges
The small parts that hold the joints even and finish the exposed edges.
| Calculator | What it does for tile |
|---|---|
| Ceramic/Porcelain Tile Spacer Count Calculator | The spacers a floor or wall takes, from the tile count and a sharing factor. |
| Tile Levelling Clip and Wedge Calculator | Levelling clips counted from the joint length, and the far smaller number of wedges. |
| Tile Edge Profile (Trim Strip) Linear Footage Calculator | Metal or plastic trim for exposed tile edges, with waste. |
Substrates and membranes
The board and the membrane under a tiled floor or wall.
| Calculator | What it does for tile |
|---|---|
| Tile Backer Board Calculator | Cement backer board, screws and joint tape for a tiled wet area. |
| Floor Crack Isolation Membrane Coverage Calculator | Rolls of crack isolation membrane beneath a tile floor over a slab. |
Wet rooms and falls
The fall to a drain and the tanking of a room with no tray and no threshold.
| Calculator | What it does for tile |
|---|---|
| Wet Room and Curbless Shower Floor Fall Calculator | The fall of a wet room or curbless shower floor to its drain: the depth at the walls, the screed and the area to tank. |
| Wet Room Tanking and Waterproof Membrane Calculator | Membrane, primer and reinforcing tape for a wet room, in two coats, with the junctions counted apart. |
Whole jobs, taken off
A job takeoff asks for the dimensions once and returns every line the job needs, each from its own calculator. These are the ones where tile is a main line.
- Tile a wall
Backer board, tile, adhesive and grout for a tiled wall, splashback or hearth surround.
- Kitchen splashback
Worktop area, tile and adhesive for the run between a counter and the wall units.
- Shower enclosure
Tanking, backer board, tile and adhesive for the walls and tray area of a shower.
- Wet-room tanking
Liquid membrane, isolation layer and backer board for a room with no tray and no threshold.
- Heated bathroom floor
Hydronic loop or electric mat, crack isolation, tile and adhesive for a warm tiled floor.
Read an answer backwards
When you start from what you hold and want to know what it will cover, these pages run the same calculators in reverse.
Worked examples
A job worked through with its inputs and its working shown, so you can see the figures before you enter your own.
- Bathroom gutted and retiled
A bathroom stripped and retiled: the tile counts for the floor and walls, the diagonal waste, the backer board and membrane, the thinset, the grout and the edge trim, in the order they are bought.
- A small bathroom floor, in tiles and boxes
Floor tile for a 40 sq ft bathroom in a plank tile laid in an offset bond
- A tiled bathroom wall, in kilograms of grout
Grout for 8.5 m² of bathroom wall tiled in 600 mm by 300 mm porcelain
Reference tables
- Production rates by operation
How long each operation takes one person, in person-hours per unit of work.
Guides
The practice behind the numbers: how the work is done, what goes wrong and how to check it.
- Setting Floor Tile
Floor tile is set out before it is set: the first two lines you strike decide every cut, joint and threshold in the room.
- Setting Out Wall Tiles in a Bathroom
A bathroom wall offers more datums than a grid of courses can honour — rim, ceiling, niche, window — and setting out is choosing which one gets the full course.
- Falls, Tanking and the Gully in a Wet Room Floor
A walk-in shower cut into a floor that already exists: the depth budget under it, the gradient band the codes barely leave open, and the tanking above it.
- Tiling a Commercial Kitchen Floor
Quarry tile priced the way a kitchen fails it: falls to the gullies, ten-millimetre joints in chemical-resistant grout, a trim on every edge that stops.
- Laying Outdoor Porcelain on a Full Mortar Bed
Vitrified porcelain has no suction, so nothing sticks to it by accident: bed depth, sand grade, slurry primer and joint width all become specifications.
Terms
How the numbers are worked out
Every calculator names the method it uses and the standard or guidance behind it. These are the methods the most of the calculators above rest on, and the published documents they cite.
Methods
- Quantity, Waste and Rounding
Why a material count is a ceiling function rather than a division, and why the waste factor — not the geometry — carries the risk. Applies to 10 of the calculators above.
- Coverage Rate and Spread
How a datasheet figure becomes an order quantity, why it is quoted per coat and calculated for a smooth plane, and what a real substrate does to it. Applies to 2 of the calculators above.
- Mass from Volume and Density
Why a rolled steel section's mass is read from a table rather than computed, why one material has five densities, and why a tonne of wet sand is less sand. Applies to 2 of the calculators above.
- Cut Lists and Bin Packing
Why sheet and length counts are a packing problem, why kerf is charged per cut, and why the optimiser is a heuristic rather than an optimum. Applies to 1 of the calculators above.
- Sealant Joints: Volume, Shape Factor and Movement
Why a sealant twice as deep is worse rather than better, why three-sided adhesion destroys a joint that never saw its rated movement, and why a firestop is a tested assembly rather than a tube of product. Applies to 1 of the calculators above.
- Spacing, Pitch and the Count That Follows
Why a run divided by a spacing gives the number of gaps and not the number of things, why the division rounds up rather than to nearest, and what the leftover bay at the end does to both. Applies to 1 of the calculators above.
Standards cited
- International Plumbing Code
United States. Cited by 1 of the calculators above.
Frequently asked questions
- How much waste should I allow for tile?
- The floor and wall tile calculator cites the TCNA Handbook and BS 5385, which give a lower allowance for a straight lay and a higher one for a diagonal or herringbone pattern. The diagonal page counts the cut at each perimeter position, and the mosaic page uses a lower allowance for mesh-backed sheets.
- How much tile adhesive do I need?
- The trowel notch matters more than the tile, because it sets the mean thickness of the bed. The tile adhesive and thinset calculators take the notch size and give bags from published data sheet rates, with a multiplier where the tile is back-buttered or bedded solid.
- How is the grout worked out?
- From the joint geometry and not from a coverage table. The grout calculator takes the share of the surface that is joint, from the tile size and the joint width, multiplies it by the area and the joint depth, then by the density of the mixed grout, and gives the answer by weight and in bags.
- Why does tanking take two coats in the calculator?
- Liquid-applied tanking is specified in two coats, the second at right angles to the first, and published coverage rates are per coat, so the tanking calculator doubles the area before dividing. It counts the reinforcing tape at internal junctions and the collars at pipes separately.
- How many levelling clips do I need?
- Clips are counted from joint length and not from tile count: each tile contributes its length plus its width of shared joint, and a clip goes at intervals along every joint. The page also counts wedges, which are reused and so are bought in far smaller numbers than the clips that snap off.