Tile Calculator — Tiles, Boxes, Thinset and Grout
Enter the area and tile size to get tiles, boxes, thinset and grout. Diagonal and herringbone layouts get a bigger waste allowance automatically.
Take this list to the store
We'll email the quantities above, what you typed in, and a link that reopens this calculator already filled in — so you can adjust it on your phone in the aisle.
How to work it out
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Measure the area
Length × width of each rectangle. For a bathroom floor that wraps around a vanity, add a section for each part rather than guessing an average.
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Find the tiles per box
It is printed on the box and on the shelf label, and it changes with every size — a box of 12 × 24 might hold 6 tiles where a box of subway holds 80. Getting this right is what makes the box count usable.
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Pick the layout before the waste
A straight or offset grid wastes about 10%. Diagonal wastes 15% because every edge tile is a cut. Herringbone and chevron waste 20%. Choosing the layout here changes the number of tiles, not just the look.
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Buy the extra box
Buy one box more than the calculator says and keep it sealed. Tiles are made in batches and the color shifts between them — a box bought six months later for a repair will not match.
Tiles needed by area
Including 10% waste for a straight layout.
| Area | 12 × 12 in. | 12 × 24 in. | 3 × 6 in. subway |
|---|---|---|---|
| 40 sq ft | 44 | 22 | 352 |
| 60 sq ft | 66 | 33 | 528 |
| 80 sq ft | 88 | 44 | 704 |
| 100 sq ft | 111 | 56 | 881 |
| 120 sq ft | 132 | 66 | 1056 |
| 150 sq ft | 165 | 83 | 1320 |
| 200 sq ft | 221 | 111 | 1761 |
| 300 sq ft | 330 | 165 | 2640 |
Divide by the tiles per box to get boxes — the calculator above does it for you.
Waste allowance by layout
| Layout | Waste | Why |
|---|---|---|
| Straight grid | 10% | Cuts only at the edges. |
| Brick or offset | 10% | Similar, with a half tile starting alternate rows. |
| Diagonal | 15% | Every perimeter tile is a triangle, and the cut-off rarely fits anywhere. |
| Herringbone / chevron | 20% | Angled cuts at both ends of every edge piece. |
| Any layout, room under 40 sq ft | 15% | Small rooms are nearly all edge, so proportional waste is higher. |
How many 12x24 tiles in 100 square feet?
Each 12 × 24 in. tile covers 2 sq ft. One hundred square feet plus 10% waste is 110 sq ft, so you need 55 tiles. At six tiles per box that is ten boxes, which gets you 60 tiles — a comfortable margin.
How much thinset and grout?
Thinset: a 50 lb bag covers roughly 95 sq ft with a 1/4 in. square-notch trowel. Large-format tile needs a bigger notch and a medium-bed mortar, which drops coverage to around 60 sq ft a bag.
Grout: about 1 lb per 9 sq ft for 12 × 12 tile with 1/8 in. joints. Narrower joints or bigger tiles use less; mosaic and subway with wide joints can use three times as much.
Sanded or unsanded grout?
- Joints 1/8 in. and wider — sanded. The sand stops it shrinking and cracking.
- Joints under 1/8 in. — unsanded, or it will not pack into the gap.
- Polished marble or glass — unsanded whatever the joint width, because sand scratches the face.
Check the boxes before you start
Open every box and check the batch or shade number printed on the end. They should match. If two batches are unavoidable, mix tiles from both across the whole floor rather than doing half the room from each — a gradual blend reads as natural variation, a hard line reads as a mistake.
Working out a shower surround
A shower is several surfaces, and the easiest way to get it wrong is to treat it as one.
Take a standard 3 × 5 ft alcove tiled to 7 ft:
- Back wall: 5 × 7 = 35 sq ft
- Two end walls: 3 × 7 × 2 = 42 sq ft
- Floor: 3 × 5 = 15 sq ft
That is 92 sq ft of wall and floor. Add a section above for each surface and let the calculator total them.
Two things to add on top: the shower floor usually takes a different tile — mosaic, so it can follow the fall to the drain — and a niche needs tile on its base, back and two sides, which is another 4 to 6 sq ft that is entirely cuts.
Use 15% waste on a shower whatever the layout. It is a small area with a high proportion of edges.
Which way to lay large-format tile
Tiles 15 in. or longer on any side need more care than a 12 × 12.
Stagger a running-bond layout by no more than a third of the tile length, not a half. Large tiles have a slight crown along their length, and a 50% offset puts the highest point of one tile against the lowest of the next — which is how you end up with lippage you can feel underfoot.
They also need a flatter substrate, a larger notched trowel, and usually back-buttering to get full coverage. Budget more thinset than the bag chart suggests.
How this is worked out
No black box — here is the arithmetic the calculator runs, so you can check it against your own numbers.
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area = length × width, summed over every sectionEach rectangle is added, so alcoves and L-shapes total correctly. -
× (1 + waste ÷ 100)10% straight, 15% diagonal, 20% herringbone — angled cuts leave unusable cut-offs. -
÷ area per tile, rounded upGives the tile count. A 12 × 24 in. tile is 2 sq ft. -
÷ tiles per box, rounded upBoxes are the smallest unit you can buy. -
thinset = area ÷ 95 bagsA 50 lb bag covers about 95 sq ft with a 1/4 in. square-notch trowel. -
grout = area ÷ 9 lbRoughly 1 lb per 9 sq ft for 12 × 12 tile with 1/8 in. joints.
Common questions
How much extra tile should I buy?
Ten per cent on top of the area for a straight layout, fifteen for diagonal, twenty for herringbone. Then one extra box beyond that, kept sealed, for future repairs — replacement tile from a different batch will not match.
How many 12x12 tiles in a box?
Usually 10 to 15, so a box covers 10–15 sq ft. It varies by manufacturer, so read the box rather than assuming — that is the number this calculator asks for.
Does tile size change how much waste I need?
Yes, in small rooms. Large tiles in a small or awkward room waste proportionally more because nearly every tile gets cut. In a bathroom under 40 sq ft, use 15% even for a straight layout.
How much does a bag of thinset cover?
Around 95 sq ft per 50 lb bag with a 1/4 in. square-notch trowel. Larger notches for big tiles cut that to roughly 60 sq ft, and back-buttering large format reduces it further.
Do I need to deduct for a bathtub or vanity?
You can, but most tilers do not on small rooms — the deduction is close to the waste you would have needed anyway. For a large kitchen with a big island it is worth measuring the island out.
How do I calculate tile for a wall instead of a floor?
The same way — enter the wall's width and height as one section instead of a floor's length and width. For a shower surround, add a section per wall.
What size trowel do I need?
1/4 × 1/4 in. square notch for tiles up to 12 × 12, 1/2 in. for large format, and 3/16 in. V-notch for mosaic. The trowel size is what determines how far a bag of thinset goes.
Can I use this for backsplash tile?
Yes. Measure the width and height of the backsplash area as a section. Backsplashes are small and mostly edges, so use the 15% waste option even for a straight layout.
Where these figures come from
Every figure below is traceable. How we check the numbers explains how they are verified, and the coverage reference collects them all in one place.
- Tile Council of North America handbook — waste allowances by layout and substrate preparation
- ANSI A108 / A118 — mortar coverage and trowel notch sizing
- Custom Building Products and Mapei data sheets — bag yields for thinset and grout at stated joint widths
Think a number here is wrong? Tell us — we check every report, correct the page, and date the change. Last checked September 11, 2026.