Tile count, mortar, grout, and every tool — for floor or wall.
Based on the dimensions on the left — edit them to match your project and this updates as you type.
110 tiles — includes 10% waste factor
Tip: Buy 5–10 extra and keep them. Future repairs need matching tiles, and discontinued patterns are impossible to find.
Coverage ~40 sq ft per bag depending on notch size
Tip: Use a 3/16" V-notch for wall tile, 1/4" square notch for floor tile.
3/16" grout lines — ~50 sq ft per bag
Tip: Unsanded grout for joints under 1/8", sanded for joints 1/8" and wider.
You need different notch sizes for floor vs. wall — get a set
Rubber float for spreading and working grout into joints
3/16" spacers — consistent grout lines every time
Seal grout after it cures — protects from stains, required in kitchens and bathrooms
You'll need cuts. Rent a wet saw from HD for $50/day or buy a snap cutter for straight cuts.
Don't forget
Grout haze remover — after grouting, a film forms on tile faces that's hard to remove once it hardens. Get it while you're at the store.
Ten percent is the right allowance for a straight grid in a room with square corners. It is the wrong allowance for most other jobs, and the difference is geometry rather than carelessness.
The waste control above defaults to 10 and goes to 20. Set it before you look at the tile count, not after.
Rectified tile has its edges mechanically ground square after firing, so every piece is effectively the same size. That is what allows a tight joint — down to about 1/16 inch. Tile that is not rectified comes out of the kiln with real variation between pieces, and a joint around 3/16 inch is what hides it. Try to run a tight line with non-rectified tile and the grout lines visibly wander within a few rows, which cannot be corrected afterwards.
The joint width then picks the grout. Unsanded below 1/8 inch, sanded at 1/8 and above — the sand is what gives a wider joint enough compressive strength not to crack. The exception is soft or polished faces, marble and glass especially, where sand can scratch the surface during grouting. Use unsanded or a specialty grout there and follow the tile maker's guidance over any general rule.
This calculator allows one 50 lb bag per 40 square feet. That figure assumes a 1/4 inch square-notch trowel, which is the normal choice for tile up to around 12 × 12. Step up to large-format tile and you step up the notch — a 1/2 inch notch lays roughly twice the mortar per square foot, so the same room can need close to double the bags. Buy accordingly if you are setting 18 × 18 or larger.
The thing to check is contact, not thickness. Industry guidance is 80 percent mortar coverage behind a tile in a dry area and 95 percent in a shower or outdoors. Set your first few tiles, pull one straight back up, and look at the back. Ridges with bare gaps between them mean the notch is too small or the mortar skinned over before the tile went down.
Tile is fired in batches and the colour shifts between them. Order the whole job at once and check that every box carries the same lot number before you open any of them — a top-up ordered a week later can arrive visibly different under the same light. Keep a spare box after the job, somewhere dry. A cracked tile in three years is a twenty-minute repair if you have a match and a floor-wide problem if you do not.
One more check before you buy: the PEI rating. I and II are rated for walls and light duty only, III suits a normal residential floor, IV and V are built for heavy traffic. Putting wall tile on a floor is the common expensive mistake — it is thinner and softer, and it crazes underfoot. The other direction is fine, weight and substrate permitting.
At the standard 10 percent waste. Every figure is this page's own formula applied to the stated tile size.
Multiply length by width for the area, add a waste factor, then divide by the square footage of one tile. A 12 × 12 inch tile is exactly 1 square foot, so 100 square feet at 10 percent waste is 110 tiles. An 18 × 18 is 2.25 square feet, so the same room takes 49. Subway tile at 3 × 6 inches is an eighth of a square foot, so it takes 880.
110, allowing the standard 10 percent waste. A 12 × 12 inch tile covers exactly one square foot, which makes this the easiest size to estimate and the reason it is the default here. Raise the waste factor and the count rises with it: 115 at 15 percent, 120 at 20 percent.
Ten percent for a straight grid layout in a room with square corners. Fifteen for a diagonal layout, because every tile along the perimeter gets cut into two triangles and one half is usually scrap. Fifteen to twenty for herringbone and chevron, where almost every edge tile is a cut. Add more again for large-format tile — a bad cut on a 24 × 24 wastes four square feet, not one — and for rooms with alcoves, jogs or an island to work around.
Unsanded for joints under 1/8 inch, sanded for 1/8 inch and wider. The sand gives a wide joint the compressive strength to resist cracking, which is why it is not optional on floors with normal joints. The exception is soft or polished surfaces — marble, glass, some polished porcelain — where sand can scratch the face during grouting. For those, use unsanded or a specialty grout and check the tile manufacturer's guidance first.
The tile decides, not taste. Rectified tile has mechanically squared edges and near-identical dimensions, so it can take joints as tight as 1/16 inch. Non-rectified tile comes out of the kiln with real size variation, and a joint of around 3/16 inch is what absorbs it — go tighter and the lines visibly wander. Check whether your tile is rectified before committing to a tight joint, because you cannot fix it after the first row.
This calculator allows one 50 lb bag per 40 square feet, which is about right for a 1/4 inch square-notch trowel — the normal choice for tile up to around 12 × 12. Notch size drives the number more than anything else: a 1/2 inch notch for large-format tile can halve the coverage per bag, so buy roughly double if you are setting 18 × 18 or larger. The target is 80 percent mortar contact behind the tile in dry areas and 95 percent in showers and outdoors, so pull a tile after your first few and check before you carry on.
Usually not. Wall tile is often softer and thinner than floor tile and will craze or crack underfoot. The number to look for is the PEI rating: PEI I and II are wall and light-duty only, PEI III suits normal residential floors, and PEI IV and V are for heavy traffic. Floor tile on a wall is the safe direction — the only issue there is weight, and whether the substrate and adhesive are rated for it.
Written and maintained by the BuildGuiders team. Counts use nominal tile dimensions and standard trade coverage rates; mortar coverage and grout guidance follow published industry practice, and your tile maker's instructions take precedence over any of it. Product recommendations are researched and compared against manufacturer specifications and verified buyer feedback — we do not test tile.