Tile Calculator

How many tiles do I need for 100 square feet?

Divide the area you are covering by the effective face area of one tile. A 12 × 12 in tile measures 144 in², or exactly 1 ft², so 100 ft² of floor takes 100 tiles before any allowance. Smaller formats multiply fast: 4 × 4 in ceramic tile covers 16 in², so the same 100 ft² — 14,400 in² — needs 900 pieces. Large-format porcelain works the other way. A 24 × 24 in tile covers 576 in², or 4 ft², so 25 tiles cover 100 ft². Always work in one unit system: convert the printed tile size to inches, convert your area to square inches, divide, then round up to whole pieces.

Measure the net tiled surface, not the room. For a floor, subtract the footprint of a tub, a shower base, or built-in cabinets that sit on the subfloor rather than on finished tile. For a shower wall or backsplash, measure each plane separately: wall length × height to the underside of the cabinets or to the ceiling, minus window and niche openings. Add the planes together before applying waste. Curbs, benches, and jambs are small but real, so list them rather than discovering them mid-install. This calculator counts field tile only, so keep a separate linear-foot tally for bullnose, pencil trim, and metal edge profiles.

Does grout joint width change how many tiles you need?

Yes, slightly, and the direction surprises people. Each tile occupies its own face plus half a joint on every side, so its effective footprint grows and the piece count falls. A 12 × 12 in tile with a 1/8 in joint occupies 12.125 × 12.125 = 147.02 in², about 2.1% more than 144 in². Across 100 ft² that trims the count from 100 tiles to 98. The effect scales with how small the tile is: a 2 × 2 in mosaic chip with the same 1/8 in joint occupies 4.52 in² instead of 4.00 — a 13% jump — which drops the count for 100 ft² from 3,600 pieces to 3,189.

That is why joint width matters enormously on mosaic, subway, and other small formats and barely at all on 24 × 24 in porcelain. It cuts the other way too: a narrow 1/16 in joint on 3 × 6 in subway tile leaves an effective 18.57 in², so 100 ft² takes 753 tiles instead of the 800 you would count with no joint at all. Enter the joint you actually intend to install. Grout width is also a performance decision — rectified large-format tile tolerates tight joints, pressed tile with variable edges usually does not, and wider joints help absorb small differences in tile height.

What is the difference between porcelain and ceramic tile?

The Tile Council of North America explains that porcelain tile is defined as an impervious tile with water absorption of 0.5% or less measured by ASTM C373, while non-porcelain ceramic tile absorbs more than 0.5% [1]. Because absorption is low, porcelain is usually — though not always — frost resistant, and the Porcelain Tile Certification Agency mark identifies tile that has actually been certified against the standard [1]. TCNA also notes that non-porcelain tile is generally easier to bond and easier to cut, while porcelain is harder on both counts [1]. None of this changes the piece count the calculator returns; it changes the mortar, the blade, and the labor hours behind that count.

Slip resistance is a separate specification. ANSI A326.3 is the American National Standard test method for the dynamic coefficient of friction (DCOF) of hard surface flooring materials, and since 2022 the standard also requires manufacturers to publish a product use classification based on slip resistance [4]. Ask for the DCOF value and the classification for the exact SKU, particularly for a shower floor, an entry, or a pool surround; TCNA notes that unglazed porcelain often has better slip resistance than the glazed version of the same body [1]. The tile count is identical either way, but the specification decides whether the finished floor is appropriate for the space.

How much extra tile should you buy for waste?

Ten percent is the working default for a straight grid or running-bond layout in a simple rectangular room. Push to 15% for a 45-degree diagonal, because every perimeter tile becomes a triangle and the offcuts rarely pair up, and to 18–20% for herringbone or chevron, where each course starts with a half or mitered piece. Small bathrooms with a toilet flange, a vanity, a door casing, and a threshold inside ten linear feet of perimeter justify 15% even on a straight layout. Applied to 100 ft² of 12 × 12 in tile with 1/8 in joints, those allowances give 108 tiles at 10%, 113 at 15%, and 118 at 20%.

Buy in whole cartons and keep the leftovers. Tile is fired in batches, and shade variation between production runs is normal, so a replacement tile bought two years later may not match. One spare carton stored flat and dry is inexpensive insurance against a cracked tile over a floor joist or a plumbing repair through the slab. Check the carton's stated coverage and piece count rather than assuming, because the same nominal size can ship 8, 10, or 12 pieces depending on thickness. Treat the result as a planning estimate for field tile — it is not a substitute for a layout drawing or an installer's take-off.

How much tile do I need for a 10 by 12 foot bathroom floor?

Start with 10 × 12 = 120 ft². Subtract an 8 ft² footprint for the tub and the vanity toe base that will not be tiled, leaving 112 ft² net. This bathroom has a threshold, a toilet flange, and a curb, so use 12% waste: 112 × 1.12 = 125.44 ft², which is 18,063 in². The tile is 12 × 24 in porcelain plank set with a 3/16 in joint, so each piece occupies 12.1875 × 24.1875 = 294.79 in². Dividing gives 61.3, so order 62 field tiles. At eight pieces per carton that is 7.75 cartons — buy 8 cartons, or 64 tiles, and keep the two spares.

The matching backsplash uses the same sequence. A 12 ft run of wall 18 in high is 12 × 1.5 = 18 ft², minus a 3 ft² window opening, for 15 ft² net. Add 15% for the outlet cuts and end returns: 17.25 ft², or 2,484 in². The tile is 3 × 6 in ceramic subway with a 1/16 in joint, so each piece occupies 3.0625 × 6.0625 = 18.57 in². That works out to 133.8 pieces, so order 134 tiles. Keep the two totals separate — 62 floor tiles and 134 wall tiles — because they are different SKUs, different thicknesses, and usually different grout.

How many tiles are in 100 square feet?

100 ft² = 14,400 in². Counts are rounded up to whole tiles and exclude any waste allowance.

How much extra tile should you order for each layout?

Waste is applied to net area before dividing by the effective tile footprint. Buy whole cartons and keep one spare.

What tile tolerances and standards should you check before ordering?

Requirements are quoted from TCNA's published summaries of the ANSI standards. Consult the current standard and the TCNA Handbook for full text.

Work these out first

• the area to be tiledSquare Footage Calculator
• backer board behind wet-area tileDrywall Calculator

What to do with this result

• price tile, thinset and groutMaterial Cost Calculator

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