How to Measure a Room for Tile
Quick answer: multiply length × width in feet for square footage, split L-shapes into rectangles, subtract permanent fixtures, and add 10% for cuts. Here's the full method.
- Measure the floor
- L-shapes & odd rooms
- Waste allowance
- Worked example
- Subtracting fixtures
- Common mistakes
Measure the floor
Measure the room's length and width in feet at the widest points and multiply for square footage. For walls, measure each wall's width × the height you're tiling and add them up. Keep every measurement in feet (or inches and convert) so the math stays consistent.
L-shapes & odd rooms
For an L-shaped room, split it into two rectangles, measure each, and add the areas. For a diagonal or herringbone layout, add more waste — the pattern produces more off-cuts. Irregular alcoves: tile the main rectangle and handle the alcove separately.
Waste allowance
Add about 10% waste for a standard grid layout. Go to 15% for diagonal patterns, herringbone, or large-format tiles where every cut eats more. Waste covers breakage during cutting, off-cuts that don't fit, and a couple of spare tiles for future repairs.
Worked example
A 12×12 ft room with 12×12 tiles:
- Area = 144 sq ft
- Add 10% waste → 158 sq ft of tile
- 12×12 tiles = 1 sq ft each → ~160 tiles
That spare margin is the difference between finishing clean and a mid-job trip back to the store for a box you can't match.
Subtracting fixtures
For a floor, tile everything except permanent islands or columns; subtract those. For walls, subtract the tub and counter area but not the backsplash you're actually tiling. Grout lines are minimal and usually included in the coverage math — don't subtract them.
Common mistakes
- No waste. Grid, diagonal, or herringbone all need extra.
- Mixing units. Keep feet or inches consistent throughout.
- Forgetting the pattern. Diagonal layouts eat 50% more off-cuts.
- Ordering by box without math. Count exact tiles needed, then round up.
FAQ
Measure length and width in feet, multiply for square footage, split L-shapes into rectangles, and add 10% for cuts and waste. Then divide by the tile's coverage.
A 12×12 room is 144 sq ft. With 10% waste that's ~158 sq ft of tile. With 12×12 tiles (1 sq ft each), that's about 160 tiles.
Add about 10% for standard layouts, and up to 15% for diagonal patterns, herringbone, or large-format tiles that create more off-cuts.
For a floor you usually tile everything except permanent islands or columns; subtract those. For walls, subtract the bathtub and counter area but not the backsplash you're tiling.