How much waste should I add for tile?

For a straight lay in a simple rectangular room, 5–10% covers cuts at the edges and the odd breakage; 10% is the safe standard and the default here. Step up to 15% for a 45° diagonal lay and 20% for herringbone or small mosaics, because every perimeter cut leaves an off-cut you usually cannot reuse, and the more cuts a pattern needs the more you waste. If your tile is a discontinued or one-off batch, add a couple of extra percent — you cannot dye-lot match a top-up later, so buying the attic spare now is cheaper than re-tiling a patch.

Does the grout joint change how many tiles I need?

Yes, and in the direction people don't expect. A grout joint makes each tile take up *more* floor than its bare size — a 600 mm tile with a 3 mm joint occupies a 603 × 603 mm module — so a given area is covered by slightly *fewer* tiles. The effect is small (about 1% on a 600 mm tile at 3 mm) but real, and it grows with thin tiles and wide joints: a 25 mm mosaic with a 3 mm joint loses over 20% of its count to the joints. This calculator builds the joint into the module, so the count is honest rather than optimistic.

How do I estimate odd-shaped, L-shaped, or sloped areas?

Break the space into rectangles, calculate each as its own area, and add the tile counts. An L-shaped room is two rectangles; a room with a bay is the main rectangle plus the bay. For a triangular niche, use half the bounding rectangle. For a wall with a window or door cut-out, tile the full wall area and let the waste allowance absorb the opening — do not subtract small openings, because the cuts around them generate waste anyway. Switch the tool to "By area" mode and enter each sub-area's square metres or feet, then sum the boxes.

Why does the tool buy whole boxes and leave spares?

Tiles are sold by the box, and shops will not split one. The honest answer rounds the with-waste tile count up to the next whole box, which almost always leaves a handful of spare tiles. That is a feature, not rounding error: keep the spares for the inevitable cracked tile two years from now, when the exact colour batch is long gone. The tool shows the leftover count so you know what is going in the attic.

Buy floor tiles for a living room with zero second trips

You measured a 5.4 m × 4.2 m living room (22.68 m²) and chose a 600 × 600 mm porcelain tile with a 3 mm joint. Switch to dims mode, enter 5.4 and 4.2, pick the 600 preset, leave waste at 10%. The tool says 63 tiles needed, and at 4 tiles a box that is 16 boxes (64 bought, 1 spare). Add the $32 box price and you get a $512 floor before grout and adhesive — the number you take to the showroom so you buy once, not twice.

Estimate a subway-tile kitchen backsplash

A backsplash runs 3.6 m wide and 0.6 m tall behind the counter — about 2.16 m². You picked a 100 × 300 mm subway tile laid in a brick bond with a 2 mm joint, and because brick bond means a cut at the end of every row you bump waste to 15%. Enter the area directly in "By area" mode. The tool returns the tile count and rounds it up to whole boxes, so you know exactly how many to order and how many half-tiles you will end up cutting.

Price a mosaic feature wall for a client

A designer is quoting a 2.4 m × 2.8 m feature wall (6.72 m²) in 25 × 25 mm glass mosaic sold on 300 × 300 mm sheets. Treat one sheet as the "tile": enter 300 × 300 mm with a 2 mm sheet joint and 20% waste for all the trimming a mosaic needs. Add the per-box sheet price and the tool produces the box count and the cost line for the quote in seconds, with the leftover sheets shown so the client knows they get spares.

Plank-tile a bathroom floor laid like timber

Wood-look 200 × 1200 mm plank tiles laid in a 1/3 offset across a 1.8 m × 2.5 m bathroom (4.5 m²). The long thin format and the offset pattern waste more at the ends, so 15% is realistic. Enter the room dims, pick the plank preset, set the joint to 2 mm. The result tells you the boxes to buy and, just as useful, the coverage area of your purchase so you can confirm it clears the room with margin.

Re-tile a wall and keep a matching attic spare

You are replacing 6 m² of cracked wall tile and the original batch is long discontinued. Calculate the count at 10% waste, then notice the tool's leftover figure: buying whole boxes naturally leaves a few spares. Those spares are the whole point — store them, because the next crack will need an exact match you cannot order. The leftover line tells you how big your safety margin is before you commit to the box count.

Tile Calculator — How Many Tiles and Boxes You Need

Room area + tile size + grout joint + waste → tiles, boxes, and cost — metric or imperial, browser-only.

Runs locally
Category Calculator
Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.

Area to tile

Length (m)Width (m)

Tile size

Tile width (mm)Tile height (mm)Grout joint (mm)

Waste / overage (%)

Box & price

Tiles per boxPrice per box (optional)Currency

You need

Boxes to buy

10 boxes

Tiles needed

38 tiles

Bare tiles (no waste)

34 tiles

Spare tiles

2 tiles

Area to cover

12 m²

Coverage of purchase

14.54 m²

What this tool does

A free tile calculator that turns the three numbers a tiler actually measures — the area to cover, the size of one tile, and the grout joint — into the only number you take to the shop: how many boxes to buy. Enter a floor as length × width (4 m × 3 m = 12 m²) or type the area directly, pick a tile size from the common presets (600 × 600 mm floor, 100 × 300 mm subway, 25 × 25 mm mosaic) or key in your own, set the grout joint, and the tool reports the effective tile module, the bare tile count, the count with waste, the boxes to buy, the leftover spares, and the area your purchase actually covers. Grout joints are handled the right way: a 3 mm joint on a 600 mm tile makes each tile occupy a 603 × 603 mm module, so the joint slightly *reduces* the count — the opposite of what most calculators assume. Waste is applied as a multiplier on the bare count, not a flat few tiles, so a 10% standard allowance, a 15% diagonal lay, or a 20% herringbone each scale correctly. Because tiles only ship by the box, the result rounds the with-waste count up to the next whole box and shows how many spare tiles you keep for future repairs. Add a price per box to get an instant cost estimate in USD, CNY, EUR, GBP, or AUD. Switch between metric and imperial at one click; the math is done in a single canonical unit so the two never disagree. Inputs sync to the URL so a "share this estimate" link reopens the same job. 100% client-side — no signup, no upload.

Tool details

Input: Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 14 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Calculator · Designer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Tile Calculator fits into your work

Use it for fast estimates, comparisons, and planning numbers before you make the final call.

Calculation jobs

Getting a realistic range before a purchase, plan, workout, or schedule decision.
Comparing scenarios by changing one input at a time.
Turning rough assumptions into a number you can discuss.

Calculation checks

Double-check units, dates, rates, and rounding assumptions.
Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
Save the inputs that produced an important result so you can reproduce it later.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Buy floor tiles for a living room with zero second trips
You measured a 5.4 m × 4.2 m living room (22.68 m²) and chose a 600 × 600 mm porcelain tile with a 3 mm joint. Switch to dims mode, enter 5.4 and 4.2, pick the 600 preset, leave waste at 10%. The tool says 63 tiles needed, and at 4 tiles a box that is 16 boxes (64 bought, 1 spare). Add the $32 box price and you get a $512 floor before grout and adhesive — the number you take to the showroom so you buy once, not twice.
Estimate a subway-tile kitchen backsplash
A backsplash runs 3.6 m wide and 0.6 m tall behind the counter — about 2.16 m². You picked a 100 × 300 mm subway tile laid in a brick bond with a 2 mm joint, and because brick bond means a cut at the end of every row you bump waste to 15%. Enter the area directly in "By area" mode. The tool returns the tile count and rounds it up to whole boxes, so you know exactly how many to order and how many half-tiles you will end up cutting.
Price a mosaic feature wall for a client
A designer is quoting a 2.4 m × 2.8 m feature wall (6.72 m²) in 25 × 25 mm glass mosaic sold on 300 × 300 mm sheets. Treat one sheet as the "tile": enter 300 × 300 mm with a 2 mm sheet joint and 20% waste for all the trimming a mosaic needs. Add the per-box sheet price and the tool produces the box count and the cost line for the quote in seconds, with the leftover sheets shown so the client knows they get spares.
Plank-tile a bathroom floor laid like timber
Wood-look 200 × 1200 mm plank tiles laid in a 1/3 offset across a 1.8 m × 2.5 m bathroom (4.5 m²). The long thin format and the offset pattern waste more at the ends, so 15% is realistic. Enter the room dims, pick the plank preset, set the joint to 2 mm. The result tells you the boxes to buy and, just as useful, the coverage area of your purchase so you can confirm it clears the room with margin.
Re-tile a wall and keep a matching attic spare
You are replacing 6 m² of cracked wall tile and the original batch is long discontinued. Calculate the count at 10% waste, then notice the tool's leftover figure: buying whole boxes naturally leaves a few spares. Those spares are the whole point — store them, because the next crack will need an exact match you cannot order. The leftover line tells you how big your safety margin is before you commit to the box count.

Common pitfalls

Forgetting waste entirely. Ordering the exact bare count means one broken tile or one mis-cut sends you back to the shop — and a top-up box rarely matches the original dye lot. Always carry at least 10% waste, more for diagonal or mosaic layouts.
Subtracting small door and window openings from a wall. The cuts you make around an opening generate off-cut waste anyway, and subtracting the opening's area usually leaves you short. Tile the full wall area and let the waste allowance cover the cut-outs.
Mixing the tile unit and the room unit. The tile size is in millimetres or inches while the room is in metres or feet. Entering "600" for a tile in a calculator that expects metres silently produces nonsense. This tool keeps tile size and room size in clearly separate units and converts internally so they cannot be crossed.

FAQ

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Tile Calculator — How Many Tiles and Boxes You Need

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Tile Calculator fits into your work

Calculation jobs

Calculation checks

Good next steps

Real-world use cases

Buy floor tiles for a living room with zero second trips

Estimate a subway-tile kitchen backsplash

Price a mosaic feature wall for a client

Plank-tile a bathroom floor laid like timber

Re-tile a wall and keep a matching attic spare

Common pitfalls

FAQ

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