Tile Calculator

What this tile calculator does

This calculator works out how many tiles you need (and how many boxes to buy) for a floor, wall, or backsplash area, given the area dimensions, the tile size, the grout-gap width, and the waste factor. It supports any rectangular tile from 1 × 1 mosaic up to 24 × 48 large-format porcelain. The result is rounded up to whole tiles and whole boxes — there are no partial tiles for sale and tile boxes are sealed.

How to use the tile calculator

1. Pick whether you are tiling a floor, wall, or backsplash. (The choice only affects the waste guidance, not the math.)
2. Enter the area length and width in feet. For a kitchen floor that is L-shaped, calculate each rectangle separately and add the tile counts.
3. Enter the tile width and tile height in inches. A 12 × 24 subway-style floor tile uses 12 and 24; a hexagonal mosaic uses the bounding-box dimensions.
4. Enter the grout gap in inches. 1/8 inch (0.125) is the common default for porcelain floor tile; 1/16 inch (0.0625) for tight rectified tile; 1/4 inch (0.25) for rustic stone or handmade tile.
5. Enter how many tiles come per box — read it off the box label or the manufacturer’s spec sheet.
6. Slide the waste factor. 10 % minimum; bump for diagonal, herringbone, or mosaic layouts. The calculator updates live.

Why 10 % waste is the minimum

Tile is unforgiving in the order math in a way that drywall and paint are not. Three things eat into the order:

• Cuts at the perimeter. Every floor edge against a wall, every cabinet kick, every door jamb needs a tile cut to fit — and the cut-off piece almost never finds a use on the next row.
• Breakage in transport and install. Porcelain tile is brittle; a few will break in the box, more will break under the wet saw, and a few will chip at the corner during install.
• Dye-lot matching. Tile is fired in batches and dye lots vary slightly. If you under-order by even three tiles and have to return to the store, the new box may be a noticeably different shade. You need extras from the original purchase.

10 % gets you safely through cuts and breakage on a straight grid layout. 15 % is the standard for diagonal layouts, herringbone, and chevron — every perimeter tile is a 45° cut that leaves an unusable triangle. 20 % for hexagonal floors or mosaic sheets.

Tile sizing trends

Grout gap: smaller is not always better

Tighter grout joints (1/16 inch) look cleaner and more modern but require rectified tile — tile whose edges have been mechanically ground straight after firing. Standard non-rectified tile has a slight variation in edge dimension that needs at least 1/8 inch of grout to hide.

Wider grout joints (3/16–1/4 inch) are normal for stone, handmade, and rustic tile. They give the layout a softer, more craft look and forgive small inconsistencies in the tile size.

Why it matters for the count: A 12 × 12 inch tile with 1/16 inch grout covers 144.75 sq inches. The same tile with 1/4 inch grout covers 150.06 sq inches. On a 100 sqft floor, that is the difference between 99 tiles and 95 tiles before waste. Always enter the grout gap in the calculator.

Save your extras

After the install, save 5 to 10 of the leftover tiles (and the matching tile-box label with the dye-lot number) in a closet or crawl space. Tile fashions change, retailers discontinue lines, and dye lots disappear within a year. The day a kitchen-chair leg chips a corner of a tile or a leaky pipe forces a tile lift, you will be glad you stashed extras from the original lot.

Backsplashes: a special case

Kitchen backsplashes have more cuts per square foot than any other tile job — outlets, switches, the gap under the upper cabinets, the run-up beside the range hood, the inside corners. A 30 sqft backsplash needs about the same total cuts as a 100 sqft bathroom floor. Always use 15 % waste minimum on backsplashes, and consider buying a full extra box for replacements down the road. The calculator’s “backsplash” mode prompts for 15 %.

Privacy

This calculator does its arithmetic in JavaScript on your device. There is no fetch call, no analytics on the values you enter, no server-side logging. The page works the same way offline once loaded.