Enter your room size and tile dimensions and get the number of tiles, the number of
boxes, and a thinset estimate — with a waste factor built in so you don't run
short. The math is the standard tile-area calculation (a 12×12 tile covers one
square foot) and uses industry-average coverage figures, with 10% waste by default and
15% suggested for diagonal or herringbone layouts.
Tiles, boxes & thinset·Preset and custom tile sizes·Adjustable waste factor
Read this first
These are estimates based on standard tile-area math and industry-average coverage figures,
not a substitute for your own measurements or the figures printed on the box. Always buy a
little extra — running short forces you to chase a matching dye lot that may no longer
exist. Tiles-per-box and thinset and grout coverage all vary by product, so confirm the box
count and the coverage charts on the bags you actually buy. Grout volume in particular
varies a lot with tile size, thickness, and joint width, so treat the grout figure as a
rough estimate only.
The calculator
Estimate tiles, boxes & thinset
Enter your area as length × width in feet, or switch to a direct square-foot total. Pick a tile size (or enter a custom one in inches), set the tiles per box and waste factor, and you'll get tiles, boxes, and a thinset estimate.
Use this if you've already worked out the square footage.
Defaults to 10 — change it to match the figure on the box.
10% for a straight layout; use 15% for diagonal or herringbone.
Tiles needed (with waste)
Boxes needed
Area covered
Tile area
Waste applied
Thinset (50 lb bags, ≈95 sq ft each)
Grout (rough estimate)
The grout figure is a rough estimate only. Grout coverage varies a
lot with tile size, tile thickness, and joint width — small or thick tiles and
wider joints use far more. This uses a simple ~1 bag per 100 sq ft rule
for roughly 12″ tile with 1/8″–1/4″ joints. Always confirm
against the coverage chart on the grout bag.
The math, honestly
How the tile and box counts are figured
It's all area. First find the area of one tile in square feet:
(width × height) / 144, with the tile's width and height in
inches — there are 144 square inches in a square foot, so a 12×12 tile is
exactly 1 sq ft and a 3×6 subway tile is 0.125 sq ft. Your floor
area is length × width in feet, or whatever total you enter
directly.
Tiles needed is the floor area, multiplied by the waste factor, divided
by the tile area, rounded up:
ceil( area × (1 + waste/100) / tile_area ). Boxes is
just ceil( tiles / tiles_per_box ). So a 120 sq ft floor in 12×12 tile
at 10% waste is ceil(120 × 1.1 / 1.0) = 132 tiles, or
ceil(132 / 10) = 14 boxes.
Thinset is estimated at one 50 lb bag per 95 sq ft —
ceil(area / 95) — based on a 1/4″×1/4″ square-notch
trowel, the common trowel for tiles up to about 12″. Larger tiles need a deeper
notch and more thinset. Grout is shown only as a rough estimate
(ceil(area / 100) for ~12″ tile with 1/8″–1/4″
joints), because grout volume swings widely with tile size, thickness, and joint width.
Tile sizes and area per tile
The square-foot area of each common tile size, and how many of them it takes to cover one
square foot. These are the figures the calculator uses — tile area is simply
width × height in inches, divided by 144.
Tile size
Area per tile(w × h) ÷ 144
Tiles per sq ft1 ÷ tile area
12″ × 12″
1.000 sq ft
1.0
18″ × 18″
2.250 sq ft
0.44
24″ × 24″
4.000 sq ft
0.25
6″ × 24″ plank
1.000 sq ft
1.0
3″ × 6″ subway
0.125 sq ft
8.0
4″ × 4″
0.111 sq ft
9.0
Tiles-per-square-foot is the reciprocal of the area and is shown rounded. The calculator
itself works from the exact area and rounds the final tile count up, so a few partial
tiles always become one more whole tile. Custom sizes use the same (w × h) /
144 formula.
Thinset coverage by trowel size
Thinset coverage depends mostly on the notched trowel you use, which in turn depends on
tile size. The calculator assumes a 1/4″ square-notch trowel (~95 sq ft per 50 lb
bag); bigger tiles need a deeper notch and use more, so coverage drops.
Trowel notchsquare-notch
Typical tile size
Coverageper 50 lb bag
3/16″
Mosaic & small wall tile
~115 sq ft
1/4″
Up to ~12″ tile
~95 sq ft
3/8″
12″–16″ tile
~60 sq ft
1/2″
Large-format 18″+ tile
~40–50 sq ft
The calculator uses the 1/4″ row (~95 sq ft per bag), which fits the most common
residential floor tile. If you're setting large-format tile, expect to use noticeably
more thinset and check the bag's coverage chart for your trowel.
Reading the result well
A tile count is only useful if you act on it sensibly. Four things worth knowing before
you buy.
Always add 10% waste — 15% for diagonal
Edge cuts, the odd cracked tile, and a few keepers for future repairs all eat into your count. Ten percent covers a normal straight or grid layout. For diagonal, herringbone, or pinwheel patterns, go to 15%, because angled cuts leave scrap that can't be reused. This calculator defaults to 10%; for a busy room with lots of cuts, round it up rather than down.
Match the box count to the actual box
Tiles per box varies enormously — 12×12 tiles often run about 10 per box, large-format 24×24 can be just 3 or 4, and subway or mosaic tile may come dozens to a box or as sheets. The default here is 10, but the box count is only right if you set this to the figure printed on the box you're buying.
Buy from one dye lot — and keep the spares
Tile is fired in batches, and shade varies slightly between lots. Buy all your tile, including the waste overage, from a single lot so the surface stays consistent, and keep a few leftover tiles afterward. If you crack one years later, matching an old lot at the store is usually impossible — the spares from your overage are the only reliable match.
Thinset and grout are estimates, not promises
The thinset figure assumes a 1/4″ trowel; large-format tile uses far more. The grout figure is rougher still — it swings with tile size, thickness, and joint width. Treat both as a starting point for what to buy, then confirm against the coverage charts printed on the actual bags. Round both up; a spare bag is cheap next to a mid-job supply run.
Where to buy
Got your numbers? Here's where to pick up what you need:
The terms behind the calculator, in plain English. These are background definitions, not
installation instructions — follow the manufacturer's directions and any local code
for the real thing.
Tile area
The surface one tile covers, in square feet: width × height in inches, divided by 144. It's the working unit for tile counting, because the number of tiles is your floor area divided by this figure. A 12×12 tile is exactly 1 sq ft.
Waste factor (overage)
The extra tile bought above the bare floor area — typically 10%, or 15% for diagonal and herringbone layouts — to cover edge cuts, breakage, and spares for repairs. It's cheap insurance against the much costlier problem of running short and chasing a matching dye lot.
Tiles per box
How many tiles a single carton contains. It depends heavily on tile size, so it's printed on the box rather than fixed. The calculator divides the tiles needed by this number, rounded up, to get cartons to buy. The default is 10; always confirm it against the box.
Thinset
The cement-based mortar that bonds tile to the substrate, spread with a notched trowel. A 50 lb bag of modified thinset covers about 95 sq ft with a 1/4″ square-notch trowel. Larger tiles need a deeper notch and use more, so coverage drops — see the trowel table.
Grout
The filler packed into the joints between tiles after they're set. Grout volume varies a lot with tile size, thickness, and joint width, so the calculator gives only a rough estimate (about one bag per 100 sq ft for ~12″ tile with 1/8″–1/4″ joints). Confirm against the bag's coverage chart.
Dye lot (batch)
The production run a tile was fired in. Color and shade can vary slightly between lots, so buying all your tile — plus the waste overage — from one lot keeps the surface consistent. Keep leftover tiles from that lot; an old lot is rarely matchable later.
Large-format tile
Tile with at least one edge 15″ or longer — 18×18, 24×24, and big planks. It covers area fast (fewer tiles, fewer joints) but needs a deeper-notch trowel and more thinset, and a flatter substrate. Fewer tiles per box, too, so set the box count carefully.
Square-notch trowel
A trowel with square teeth that comb thinset into even ridges; the notch depth sets how much mortar goes down. A 1/4″ notch suits tile up to ~12″; larger tile wants 3/8″ or 1/2″. Notch size, not tile alone, drives thinset coverage.
Frequently asked
Add about 10% over your measured area for a standard straight or grid layout. This covers edge cuts, the occasional cracked tile, and a few spares to keep for future repairs. For diagonal and herringbone layouts, bump the waste factor to 15%, because angled cuts leave more unusable scrap. This calculator defaults to 10% and lets you change it — try it in the calculator.
It varies by tile size, so always read the box. As a rough guide, 12×12 tiles often come about 10 to a box, 18×18 about 6 to 8, and small mosaic or subway tile can come dozens to a box or sold as sheets. Large-format 24×24 tile sometimes comes just 3 or 4 per box. This calculator defaults to 10 tiles per box; change it to match the box you're buying so the box count is right.
Not for the tile count. The waste factor already gives you a comfortable margin, and grout joints are thin enough that they don't meaningfully reduce how many tiles you need over a normal room. Where grout lines do matter is grout volume — wider joints, smaller tiles, and thicker tiles all use more grout. Use the grout figure here only as a rough estimate and confirm against the coverage chart on the bag.
A 50 lb bag of modified thinset covers roughly 95 square feet with a 1/4″ × 1/4″ square-notch trowel, the common trowel for tile up to about 12″. Larger tiles need a deeper notch and use more, so coverage drops — some large-format installs get closer to 40–50 sq ft per bag with a 1/2″ notch. This calculator estimates one bag per 95 sq ft; always check the coverage chart on the bag.
Plan on roughly 15% waste instead of 10% for a diagonal or herringbone layout. Setting tile at 45 degrees, or in a herringbone or pinwheel pattern, means more tiles are cut at angles along the walls, and those angled offcuts usually can't be reused. The extra 5% covers that scrap. Complex patterns with borders or multiple tile sizes can warrant even more, so when in doubt, round the waste factor up.
First find your area: length × width in feet, or enter the total square footage directly. Then find the area of one tile — width × height in inches, divided by 144. Tiles needed equals area × (1 + waste) ÷ tile area, rounded up. For example, a 120 sq ft floor with 12×12 tiles (1 sq ft each) at 10% waste needs ceil(120 × 1.1 / 1.0) = 132 tiles. The calculator does all of this for you.
Multiply the tile width by its height, both in inches, then divide by 144 to convert square inches to square feet — there are 144 square inches in a square foot. A 12×12 tile is 144 sq in, exactly 1 square foot. A 3×6 subway tile is 18 sq in, or 0.125 sq ft, so it takes 8 of them to cover one square foot. This per-tile area is what the tile count divides by.
Yes, where you can. Tile is fired in batches called lots or dye lots, and color and shade can vary slightly between them. Buying all your tile, plus the waste overage, from a single lot keeps the finished surface consistent. Keep a few leftover tiles from that lot afterward — if you ever crack one, matching a years-old lot at the store is usually impossible. The waste factor is what leaves you those spares.