Tile Calculator

A tile calculator answers three questions at once: how many tiles, how much thin-set, and how much grout. Most people only think about the first one — they measure a 100-square-foot floor, buy 100 square feet of 12x12 tile, and then discover at the register that nobody sold them the mortar to stick it down or the grout to fill the joints. The tile itself is often less than half the bill. Sizing all three from the start is what separates one trip to the store from three.

The Math: Turning Area Into a Tile Count

The core calculation is short. Find your area, find how much one tile covers, divide, then add waste. The only step people botch is the tile coverage, because tile is sized in inches and floors are measured in feet.

1. Surface area: Width × length in feet, added across every surface. A 10 × 8 floor is 80 square feet.

2. Coverage per tile: Tile width × length in inches, divided by 144. A 12x12 tile covers 144 ÷ 144 = exactly 1 square foot; an 18x18 covers 324 ÷ 144 = 2.25 square feet.

3. Tiles before waste: Area ÷ coverage per tile. That 80-square-foot floor needs 80 ÷ 1 = 80 tiles of 12x12, but only 80 ÷ 2.25 = 36 tiles of 18x18.

4. Add waste, then round to boxes:Multiply by 1.10 for a standard grid, then divide by the pieces per carton and round up. You can't buy two-thirds of a box. If you'd rather measure the raw area first, our square footage calculator handles odd-shaped and multi-room layouts before you ever pick a tile.

A Real 80-Square-Foot Bathroom Floor, Start to Finish

Let's tile that 10 × 8 bathroom in 12x12 porcelain with 1/8-inch grout joints. Here's the entire order, line by line:

• Area: 10 × 8 = 80 sq ft
• With 10% waste: 88 sq ft of tile to buy
• Tiles (1 sq ft each):88 tiles — at 11 per box, that's 8 boxes
• Thin-set: 80 ÷ 85 sq ft per bag = 1 bag (grab a second as backup — a partial bag is wasted anyway)
• Grout: about 9 lb — one 25 lb bag covers it with room to spare
• Tile at $3.50/sq ft: 88 × $3.50 = $308
• Setting materials: 1 thin-set bag ($16) + 1 grout bag ($20) = $36
• Labor at $8/sq ft: 80 × $8 = $640
• Total installed: $984 — about $12.30 per square foot

Look at where the money actually goes. The tile is $308, but labor is $640 — more than double. That ratio is normal for tile, and it's why tile is the most expensive common floor to install even when the tile itself is cheap. Pick a $1 builder-grade tile instead of the $3.50 porcelain and you save $220 on materials, but the $640 labor doesn't budge, so your "cheaper" floor is only about 22% cheaper.

How Many Tiles Per Square Foot, By Size

Keep this table next to you while you shop. It's the fastest way to sanity-check a box label or eyeball a job before you measure. Multiply the tiles-per-100-sq-ft column by your area in hundreds, then add waste.

The jump from 100 tiles to 3,600 tiles for the same 100 square feet isn't a typo. Mosaic sheets just bundle those tiny tiles into 12x12 mesh-backed squares, so you're really laying 100 sheets — but the grout-line count, and the labor to set them straight, scales with the tile count, not the sheet count.

Sizing Thin-Set and Grout (The Part Everyone Underbuys)

Thin-set is the mortar that bonds tile to the substrate. A 50-pound bag covers about 85 square feet of 12x12 tile with a 1/4-inch notched trowel — but only 45 square feet of large-format tile, because big tiles need a deeper 1/2-inch trowel to fully support them. Skimp here and you get hollow spots that crack tiles under foot traffic. Always round bags up; a half-used bag of thin-set goes hard in the garage anyway.

Grout fills the joints, and the amount depends on four things: tile size, joint width, tile thickness, and area. The geometry is simple — more joint length per square foot and wider, deeper joints mean more grout. The working formula is grout pounds per square foot ≈ (tile length + width) ÷ (length × width) × joint width × thickness × a density constant. You don't need to run that by hand; the calculator does it. The takeaway is that 5/16-inch-thick 12x12 tile with 1/8-inch joints needs about 0.12 pounds of grout per square foot, so a 25-pound bag covers a bit over 200 square feet. Most residential floors need a single bag.

Big Tile vs. Small Tile: The Hidden Cost Swap

Going bigger doesn't simply mean "fewer tiles, less work." It swaps one cost for another. Over the same 100-square-foot floor with 1/8-inch joints, here's how the materials shift:

Bigger tile drops your grout use by nearly half and cuts the piece count to a quarter — but it raises thin-set bags, because each one covers less area. It also demands a flatter substrate: a slab that's off by 1/8 inch over 10 feet hides fine under 12x12 tile but causes lippage (one edge sitting proud of its neighbor) under a 24x24. Big tile rewards a flat floor and punishes a wavy one.

Why Your Layout Decides Your Waste Factor

Two identical floors can need very different amounts of tile, and the only variable is the pattern. A straight grid wastes the least, around 10 percent, because cut-off pieces from one edge often start the opposite edge. Lay the same tile on a 45-degree diagonal and waste climbs to 15 percent, since every perimeter tile becomes a triangle with an unusable offcut. Herringbone and pinwheel patterns push past 20 percent.

Room shape matters as much as pattern. A long, narrow space — a hallway or a shower curb — forces more cuts per square foot than an open square room, so bump the waste up even for a simple grid. And small decorative tile in a busy backsplash, threaded around outlets and a range hood, easily hits 15 to 20 percent. If you're comparing tile against plank or sheet goods for a whole room, our flooring calculator runs the same area through hardwood, laminate, vinyl, and carpet so you can see the installed-cost difference side by side.

Five Tiling Mistakes That Cost Real Money

• Buying tile with zero waste. Ordering exactly 100 square feet for a 100-square-foot floor. Cost: a second trip, and often a mismatched dye lot because the new boxes come from a different production run.
• Forgetting the setting materials.Thin-set and grout add $50–$120 on a typical room and aren't in the tile's per-square-foot price. People walk out with tile and no way to install it.
• Wrong trowel for large tile. Using a 1/4-inch trowel under 24x24 tile leaves voids, and the tile cracks within a year. The fix is a $12 half-inch trowel and 50% more thin-set — cheap compared to a $400 re-tile.
• Skipping waterproofing in a shower. Tile and grout are not waterproof. A membrane runs $1.50–$3 per square foot, and leaving it out lets moisture rot the framing and feed mold behind the wall — the EPA's mold guidance warns that hidden wall cavities are the hardest to remediate. It's a four-figure repair.
• Ignoring trim and transitions. Bullnose edge tile, metal Schluter trim, and thresholds add $4–$10 per linear foot and never show up in the field-tile count. A small bathroom can need $60–$150 in edge pieces.

Floors, Walls, Backsplashes, and Showers Aren't the Same

The calculator changes its defaults by surface for a reason — each one behaves differently:

• Floors take the heaviest, thickest tile and the lowest waste on an open grid (10%). Labor runs $7–$10 per square foot because of substrate prep and leveling.
• Wallsuse thinner tile and need anti-sag thin-set so pieces don't slide before they cure. Labor climbs to $9–$11 because you're fighting gravity.
• Backsplashesare small in area but high in waste (15%) thanks to outlet, window, and end-cap cuts. They're the most DIY-friendly tile job in the house.
• Showers demand waterproofing behind the tile and the most labor ($12–$18) for the curb, niche, and slope-to-drain work. This is the one surface to think twice about doing yourself.

For wall and floor layouts, the U.S. tile industry follows the Tile Council of North America's installation guidelines, which spell out the substrate, membrane, and movement-joint requirements that keep tile from cracking down the line.

When This Estimate Won't Be the Whole Order

This tool sizes the field tile, thin-set, and grout — the bulk of every job. It doesn't price a few real line items, so add them when they apply. Edge trim and bullnose, a waterproofing membrane in wet areas, backer board or an uncoupling mat over wood subfloors, sealer for natural stone or sanded grout, and tile spacers plus a rented wet saw all live outside the field-tile math. On a shower, those extras can equal the tile cost.

The grout and mortar figures are planning numbers too. Real coverage shifts with trowel technique, substrate flatness, and how much mortar ends up back in the bucket. Buy one extra bag of each — they store for a while, and a mid-job run to the store costs you the better part of a day. If you're painting the walls above a backsplash or wainscoting in the same room, our paint calculator sizes that part of the job in gallons, and our wallpaper calculator handles a papered accent wall above the tile line. For a bathroom or kitchen remodel where tile is one line among many, our construction calculator folds tile into the larger material takeoff alongside framing, drywall, and the rest of the build.