Tile Calculator - Tiles, Boxes, Waste & Cost

How to use it

1. Choose how you want to measure: room length and width, or one total area figure.
2. Pick your units: feet and inches, or meters and centimeters.
3. Set the tile size from a preset or enter a custom width and height, plus the grout joint width.
4. Pick the layout pattern. The tool auto-fills a suggested waste factor that you can override.
5. Optional: add tiles per box or coverage per box to get boxes to buy and leftover tiles.
6. Optional: enter a price per tile, per box, or per square unit for a material estimate, and toggle grout, thinset, or labor add-ons.
7. Read the two headline numbers at the top of the result card, then the full breakdown below.

At a glance

• Bathroom floor, 5 ft x 8 ft (40 sq ft), 12x24 tile, straight layout, 1/8 in grout, 10% waste, 8 tiles per box, $4.20 per tile: Net 40 sq ft, effective 2.03 sq ft per tile, 20 tiles before waste. 44 sq ft with waste, 22 tiles to buy, 3 boxes (24 tiles, 2 left over). Tile cost about $100.80, roughly $2.52 per sq ft.
• Kitchen floor, 12 ft x 10 ft (120 sq ft), 12x12 tile, diagonal layout, 15% waste: Net 120 sq ft, effective 1.02 sq ft per tile, 118 tiles before waste. 138 sq ft with waste, 136 tiles to buy. Add tiles per box or coverage per box to get box counts.
• Subway backsplash wall, 10 ft x 2 ft (20 sq ft), 3x6 tile, brick / running bond, 10% waste, priced at $8 per sq ft: Net 20 sq ft, effective 0.13 sq ft per tile, 151 tiles before waste. 22 sq ft with waste, 166 tiles to buy. At $8 per sq ft that is about $176 in tile, roughly $8.80 per sq ft after waste.

How the math works

Everything is converted to one base unit first: square feet for imperial, square meters for metric. Net area is the sum of your tile areas minus the fixtures and niches you subtract. Each tile's effective footprint adds the grout joint on two sides, (tileWidth + grout) times (tileHeight + grout), because grout lines take up real space on the wall or floor. Tiles before waste is net area divided by that footprint, rounded up. The waste factor is suggested by layout (straight and brick 10%, diagonal and herringbone 15%, complex 20%) because angled and interlocking patterns force more cuts, and you can override it. Tiles to buy is the raw count times one plus the waste, rounded up. Boxes are rounded up from either tiles-to-buy divided by tiles per box, or area-with-waste divided by coverage per box. Cost multiplies your entered price by tiles purchased, boxes, or area with waste, then adds optional grout / thinset and optional labor.

1. 1. Put everything in one unit

   Room dimensions are in feet or meters, but tile and grout are in inches or centimeters, so the first job is to convert. A 12 in tile is 1 ft; a 1/8 in grout joint is 0.125 in, or about 0.0104 ft. Mixing a foot measurement with an inch measurement is the most common way a hand estimate goes wrong, which is why the tool locks you to one unit system and does the conversion for you.

2. 2. Find the net area you actually cover

   Add up each rectangle you are tiling, then subtract the parts you are not: a vanity footprint, a tub, a kitchen island, a fireplace. A 5 ft by 8 ft bathroom is 40 sq ft; drop a 2 ft by 2.5 ft vanity and you cover 35 sq ft. Tile is sold to cover area, so the net area, not the floor's outside dimensions, is what the rest of the math runs on.

3. 3. Add the grout joint to the tile footprint

   A tile does not cover its own nominal size once it is set, because every tile carries half a grout joint on each side. A 12 by 24 in tile is 2.00 sq ft nominal, but with a 1/8 in joint its effective footprint is (12.125 / 12) x (24.125 / 12), about 2.03 sq ft. The gap looks tiny, but on a big floor it is the difference between having enough tile and coming up a box short.

4. 4. Divide, then round up to whole tiles

   Raw tiles is net area divided by the effective footprint. For 40 sq ft of 12 by 24 in tile that is 40 / 2.03 = 19.7, which rounds up to 20 tiles before any waste. You always round up, because you cannot buy 0.7 of a tile and a partial tile still has to come from a full one.

5. 5. Add a waste factor for cuts and breakage

   Perimeter cuts, the odd cracked tile, and a saw that eats a tile now and then all mean you buy more than the bare coverage. A straight floor adds about 10 percent, so 20 tiles becomes 22 to buy. Diagonal and herringbone lean toward 15 percent because every edge is a cut; busy rooms with lots of jogs push to 20 percent. The tool suggests a figure from the pattern and lets you raise it.

6. 6. Turn tiles into boxes and read the leftovers

   Tile is sold by the box, not the tile, so 22 tiles at 8 per box is ceil(22 / 8) = 3 boxes, which is 24 tiles with 2 left over. Those 2 spares are the point: keep them for the tile a plumber cracks in five years, because a later box will not match. If you only know coverage per box, the tool divides the with-waste area by that figure instead.

7. 7. Price the material, keep labor separate

   Cost multiplies your own price by the quantity that matches how it is sold: per tile times tiles bought, per box times boxes, or per square unit times the with-waste area. 24 tiles at $4.20 is about $100.80. Grout and thinset ride on a separate line, and labor is off by default and shown on its own line so it never inflates the material headline.

Worked scenarios, start to finish

Real jobs with the numbers carried all the way through, so you can see how the estimate is built and check your own figures against them.

The judgement calls a pro makes

Decisions the tool cannot make for you, and how someone who does this for a living thinks them through.

How much waste to actually order

The pattern sets the floor: 10 percent for straight or brick, 15 percent for diagonal or herringbone, 20 percent for busy rooms. But count your cuts. A long narrow hallway or a room with lots of jogs, doorways and closets forces more perimeter cuts than a plain square of the same area, so nudge the figure up. Large-format tile also earns extra because each mistake costs more.

Round up to full boxes, and keep the spares

You buy whole boxes, so real waste is usually higher than your percentage once the box rounds up. Do not fight it. The leftover tiles are the only ones that will ever match your floor. Stores discontinue lines and colors drift between production runs, so a box in the garage is cheap insurance against a cracked tile years later.

Match the dye lot or batch number

Tile color is baked in production runs, and two boxes of the same product from different runs can be visibly different. Buy all your tile at once, check that every box carries the same batch or shade number, and open boxes together on the job so any variation is spread across the floor rather than pooled in one corner.

Choose the starting point and layout line

Where you start decides where the ugly cut lands. Center the field so opposite walls get equal border cuts, and avoid a sliver less than about a third of a tile against the most visible wall. This does not change the tile count much, but it decides whether the job looks planned or improvised, so dry-lay a row before you spread thinset.

Flatness for large-format tile

Tiles 15 in or longer on a side telegraph every hump and dip in the substrate, and lippage (one edge sitting proud of its neighbor) is the usual complaint. Budget for a leveling clip system and check the subfloor with a straightedge first. The calculator counts tiles, not flatness, so this is a judgement the number cannot make for you.

Common mistakes, and the fix

• × Using the nominal tile size and forgetting the grout joint.

  ✓ Always add the joint to both sides of the tile. On a large floor the joint can hide most of a box of tile, which is exactly the box you end up short.

• × Buying the raw tile count instead of full boxes.

  ✓ Round the tiles-to-buy figure up to whole boxes. A partial box does not exist at the store, and the rounding is what leaves you the spares you need.

• × Applying the same 10 percent waste to every pattern.

  ✓ Diagonal, herringbone and cut-heavy rooms need 15 to 20 percent. Under-order on a diagonal and you stop the job to reorder, often from a different dye lot.

• × Mixing feet with inches, or centimeters with meters.

  ✓ Pick one unit system and let the tool convert. A tile entered in the wrong unit throws the whole count off by an order of magnitude.

• × Ordering by tile count when the tile is sold by coverage.

  ✓ Check how the product is sold. For mosaics and many wall tiles the store thinks in square feet per box or per sheet, so enter coverage per box and price per square unit.

Material and unit specifics

Nominal vs actual size

A tile labeled 12 by 24 in is often a hair under that, and its real coverage once installed is larger than nominal because of the grout joint. This tool uses the size you enter plus the joint, so use the actual measured tile if you have it, or the label size if you do not.

Tiles per box and coverage per box

There is no universal box count. A box of 12 by 24 in porcelain might hold 8 tiles and cover about 15.5 sq ft; a box of 24 by 48 in planks might hold 2. Read the box or product page and enter tiles per box or coverage per box, and the tool works out how many boxes to buy.

Mosaic and sheet-mounted tile

Mosaics come on 12 by 12 in mesh sheets, not as loose tiles, so counting individual chips is pointless. Price and buy these by the sheet or by coverage per box. Enter the sheet as your unit rather than the tiny tile size.

Grout joint width

Common joints run from 1/16 in for rectified subway tile to 3/16 in or wider for rustic and large-format tile. The joint sets both how much tile you need and how much grout, and rectified tiles allow the tightest joints because their edges are machined straight.

Imperial and metric

US tile is sized in inches with area in square feet; most of the world uses centimeters and square meters. A 12 by 12 in tile is close to 30 by 30 cm but not identical, so switch the tool to the unit your tile is actually labeled in rather than converting by hand.

Reading your result

Buy the box count, not the raw tile count: boxes round up and the leftovers are your repair stock for a cracked tile or a future patch. The cost line is material only unless you turn on labor, which stays on its own line so the headline is never inflated. All prices are the ones you enter, so the estimate is only as good as your quotes. Cost per square foot is the grand total spread over the net area you are tiling.

Limitations

• This is an estimate, not a quote. It does not know your specific SKU, dye lot, or local labor rates.
• It assumes rectangular areas. For an L-shaped or irregular room, split it into rectangles and add each as its own area.
• It does not calculate trim, bullnose, or transition pieces, and it does not do mosaic sheet math (enter mosaic as a per-sheet or per-square-foot figure instead).
• The grout share is a simple two-sided allowance; very wide joints or unusual patterns can shift the real count slightly.

Frequently asked questions

How much extra tile should I buy for waste?

A common rule is 10 percent extra for a straight or brick layout, 15 percent for diagonal or herringbone, and around 20 percent for complex patterns or rooms with many cuts. The tool fills these in by layout, and you can raise the figure for a room with lots of corners or angles.

How many tiles are in a box?

It varies by tile and brand, so there is no single number. Check the box or the product page, then enter either tiles per box or the coverage per box in square feet and the tool works out how many boxes to buy.

Does the calculator include grout and adhesive?

Optionally. Turn on the grout / thinset / spacers add-on and enter a per-square-foot figure (about $0.75 is a reasonable default). It is added as a separate line, kept apart from the tile cost so you can see each part.

Is the cost estimate accurate?

It uses the prices you enter, so it is a material estimate rather than a firm quote. Enter real prices from your supplier for the closest figure, and remember labor is off by default and shown separately when you turn it on.

Why does the tool add the grout joint to the tile size?

Because a set tile occupies its own size plus half a grout joint on every side. Ignoring the joint undercounts tiles, and on a large floor that gap can add up to a whole box, which is how people end up short.

Should I tile the floor under the vanity or appliances?

Usually no under fixed cabinets and vanities, so subtract those areas. Do tile under a fridge or a freestanding range so it sits level and you can slide it out. When in doubt, tile a little past the visible edge and subtract only the fully hidden footprint.