Tile calculator: how much tile do I need?
Measure the floor or wall, enter the tile size, and pick a straight or diagonal layout. You get the tile count with extra for cuts, boxes if you know the box count, and about how much grout.
- Straight or diagonal
- Boxes from the label
- Grout amount
Grout is figured for joints as deep as the tile is thick, plus 10% for waste. Check the coverage chart on your grout bag, since density varies by product.
Before you tile
How it works
Tiles = area × (1 + extra) × 144 ÷ (tile length × tile width in inches), rounded up. Extra defaults to 10% for a straight layout and 15% for diagonal, the usual allowances for cuts and breakage.
Boxes = tiles ÷ tiles per box, rounded up. Leave it blank if you don't know the box count yet.
Grout volume per square foot = 144 × (tile length + tile width) ÷ (tile length × tile width) × joint width × joint depth, in cubic inches. Joint depth is the tile thickness.
Grout weight uses about 0.06 pounds per cubic inch, plus 10% for waste. That density matches Custom Building Products' published chart, where 25 pounds of sanded grout covers about 373 square feet of 12x12 tile with 1/8-inch joints.
About this tool
Who it's for
For anyone tiling a bathroom floor, a backsplash or a shower wall.
Example
You enterAn 8x5 bathroom floor, 12x12 tile, 1/8-inch joints, straight layout
You get44 tiles and about 3 pounds of grout.
What's different
- Changes the extra for straight or diagonal layouts.
- Figures grout from your real joint size.
- Gives boxes once you know the box count.
Gotchas and tips
- Large or patterned tile can need more than 15% extra.
- Grout joint width changes grout use a lot. A 1/16-inch change can double it.
- Keep a few spare tiles for future repairs.
Privacy: Runs entirely in your browser. Nothing you type is sent to us, and anything it remembers is saved on this device only.
Built and maintained by the GrabTheHammer team, using published figures from manufacturers and agencies, listed below. Updated November 2026. Spot a problem? Tell us.
Tile questions
How much extra tile should I buy?
About 10% for a straight layout and 15% for a diagonal one. Buy a little more for large tile or patterns, and keep a few spares for repairs later.
How much grout do I need?
It depends on the tile size, joint width and depth. For 12x12 tile with 1/8-inch joints, a 25-pound bag of sanded grout covers about 370 square feet. Smaller tile and wider joints use much more.
Sanded or unsanded grout?
Check the bag for the joint widths it is made for. Unsanded grout is meant for narrow joints and sanded grout for wider ones.
Sources: CLE Tile: how much extra tile to buy; Custom Building Products grout coverage chart; LATICRETE: 10% grout waste rule.