Tile Calculator
Calculate tiles, boxes, thinset, grout, and spacers for any tile project. Works for floors, walls, kitchen backsplashes, and bathroom showers — any size tile, any layout.
How much tile do I need?
Default: a 10 × 12 ft floor with 12 × 12 in tiles.
What you'll need to buy
Prices approximate · Links go to retailer search results
- Porcelain Floor Tile (SKU varies by style)Choose pattern and finish at checkout. Count here is boxes.
- Modified Thinset Mortar — 50 lb~70-90 sq ft
- Sanded Grout — 25 lb
- Tile Spacers — 100-count
- Notched Trowel (1/4" or 1/2")
- Grouting Sponge (2-pack)
Estimated total: ~$785 (materials, before tax)
Product links go to Home Depot search results — pick the best match for your project. Prices shown are rough averages.
How we calculated it
Tile math has three independent parts that most calculators get wrong. This calculator handles them separately:
- Tile count. Room area ÷ tile area, plus waste factor. A 12×12" tile is exactly 1 sq ft; a 6×24" plank tile is 1 sq ft; a 2×2" mosaic is 0.028 sq ft.
- Thinset coverage. Varies by trowel notch size, which varies by tile size. Rough rule: 1×50 lb bag per 90 sq ft for 12" tiles, per 70 sq ft for 16", per 50 sq ft for 18"+.
- Grout weight. Smaller tiles and wider joints = more grout. A 12×12" tile with 1/8" joints needs ~0.5 lb/sq ft; a 2×2" mosaic with 1/8" joints needs ~1.2 lb/sq ft; a 24×24" tile with 1/16" joints needs ~0.2 lb/sq ft.
Waste factors: 10% straight-lay, 15% diagonal, 20% herringbone or mosaic. If the room has lots of niches, add 5% more. Always buy extra — dye lots can shift between batches and mid-project returns often cannot be matched.
Frequently asked questions
How many 12x12 tiles do I need for a 100 sq ft floor?
A 12x12 tile covers exactly 1 sq ft, so a 100 sq ft floor needs 100 tiles plus waste — 110 for straight-lay, 115 for diagonal, 120 for complex patterns. At 10 tiles per box, that is 11-12 boxes.
How much thinset do I need per square foot of tile?
Depends on tile size. Small tiles (≤12"): 1 × 50 lb bag per 80-100 sq ft with a 1/4" notched trowel. Large format (12-16"): 1 bag per 70 sq ft with a 1/2" notch. Extra-large (≥18"): 1 bag per 50 sq ft. Always add 10% for back-buttering large tiles.
How much grout do I need?
Rough rule: 1 pound of grout per 2 sq ft for 12" tiles with 1/8" joints. Smaller tiles or wider joints need more — mosaic with 3/16" joints can need 1 lb per sq ft. This calculator computes it from your actual tile size and joint width.
Sanded or unsanded grout — which do I need?
Sanded grout for joints 1/8" and wider (floor tile, most bathroom tile). Unsanded grout for joints 1/16" or narrower (polished marble, glass mosaic). Using unsanded in wide joints cracks within a year; using sanded in narrow joints scratches polished tile.
What waste factor should I use for tile?
10% for straight-lay on a simple rectangular room. 15% for diagonal lay (more cuts). 20% for herringbone or complex patterns. 25% for a room with lots of niches, closets, or transitions. Over-ordering costs little; returning to the store for 2 extra tiles usually means a dye-lot mismatch.
Do I need cement board under tile?
Floor tile: yes — use 1/4" cement board (CBU) over plywood subfloor. Wet areas like showers: use waterproof CBU or a membrane system (Schluter Kerdi). Drywall alone is not a valid tile substrate on floors or in showers.
How do I plan where tile cuts fall?
Start by finding the center of the room and dry-lay a row in each direction. Adjust so cuts at the walls are at least half a tile wide. Tiny slivers at walls look like mistakes. If the room is symmetrical, center a full tile or center a grout line — whichever makes the edge cuts larger.
Porcelain vs ceramic — which is better?
Porcelain is denser, less porous, and stronger — use it for floors, high-moisture areas, and outdoor tile. Ceramic is fine for walls and backsplashes, slightly cheaper, easier to cut. If you are unsure, porcelain is rarely the wrong call.
How long does a tile floor take to install?
About 1 sq ft per minute for a DIYer including layout, cuts, thinset, and setting the tile. A 100 sq ft room: one full day of tile-setting plus 24 hours cure, then 2-3 hours of grouting the next day. Pros are ~3x faster.
Can I tile over existing tile?
Technically yes if the old tile is sound — use a modified thinset rated for tile-on-tile and rough up the surface with a grinder. But floor height goes up 3/8-1/2", which causes door and transition issues. Usually easier to rip and replace.
Other calculators
Related terms
Plain-English definitions for the terms used in this calculator.
- thinset
- The cement-based adhesive used to bond tile to substrate. Modified thinset adds polymers for flex and bond strength — required for most floor tile. 50 lb bag covers 50-90 sq ft depending on trowel notch size.
- grout
- The filler material between tiles. Sanded grout for joints 1/8" and wider; unsanded for narrower joints on polished stone or glass. Epoxy grout is most durable but harder to work with.
- CBU (cement board)
- Cementitious backer unit — a rigid waterproof substrate (Hardibacker, Durock, Wonderboard) installed under floor and wet-area tile. Replaces plywood or drywall anywhere tile goes in wet or high-moisture zones.
- waste factor
- An over-order multiplier to account for cuts, damage, errors, and touch-ups. 10% is standard for simple jobs; 15-20% for complex layouts (diagonal tile, cathedral ceilings, rough subgrades).