Understanding your result
The headline is the field of whole tiles, so many along the length by so many across the width, and under it the cut widths at each wall in both directions. The stats give the number of rows, the tiles per row and the smallest cut anywhere on the floor. Below the stats the diagram draws the grid to scale so you can see where the cuts fall, and the table lists each direction separately with the balanced alternative for each: what the cuts would be if you switched between centring a tile and centring a joint.
Read the two cut tiles at the walls rows first. Equal cuts at opposite walls are what a centred layout buys you; a full tile at one wall gives a single cut at the other, which is only a good idea when that cut is large and the far wall is hidden. If either cut is under the minimum you set, the note under the table says which direction has the problem and whether the other balanced start fixes it. If neither does, the choices are a border, a tile of a slightly different size or living with a full tile at the most visible wall.
The rows and tiles per row figures include the cut pieces, so they are the real count of pieces you will handle. For the number to buy, including waste, take the same room and tile to the floor tile calculator. For planks laid in rows with staggered ends, which have their own last-row problem, the plank layout calculator does the equivalent arithmetic, and for a 45° or herringbone pattern the diagonal and herringbone calculator works out the pieces and the starting line.
How we calculate this
Each direction is worked out on its own: the tile length and the room length give the cuts along the room, the tile width and the room width give the cuts across it. A joint’s width is left at each wall as the expansion gap, which is why the cut tile is the leftover minus one joint. When the leftover is smaller than a joint the calculator reports no cut and full tiles fitting exactly, with the walls taking a slightly narrower gap. The guide to tile size and grout joint explains how the joint width moves the layout, and the large-format tile guide covers the one-third offset and the leveling that large tiles add on top of the layout.
The assumptions behind the numbers
| Assumption | Default | Where it comes from |
|---|---|---|
| Tile and joint | 24 × 12 in, 1/8 in joint | Common floor tile; TCNA Handbook minimum joint for non-rectified tile |
| Wall gap | one joint width | Tile is kept a joint’s width off the wall for movement and caulked; TCNA EJ171 calls for a movement joint at the perimeter |
| Smallest acceptable cut | 2 in (5 cm) | Installer practice; one third of a tile is the usual target for a deliberate look |
| Tile orientation | tile length along the room length | Change the tile dimensions round to lay the tile across the room |
| Room | 12 × 10 ft (3.6 × 3 m), rectangular and square | Chosen for the example; the room must be measured at both ends in practice |
Assumptions last reviewed October 7, 2026.
The calculator treats the room as a true rectangle and the walls as straight. It does not know about doorways, which usually get a full or near-full tile at the threshold and therefore set the grid in one direction, or about a tub, a vanity or an island, which hide a cut and make it free. Those are judgements for the diagram: look at where the cuts fall and move the grid by half a pitch if a visible wall gets the sliver and a hidden one gets the full tile. Brick and offset patterns have the same cut widths along the rows but a staggered cut at the row ends; the guide to plank direction and the last row covers that case for planks and plank-shaped tile.
Two worked examples
A 14 × 12 ft kitchen in 24 × 12 tile, tile centred
1/8 in joint, tile length along the 14 ft wall.
- Pitch: 24.125 in along the length, 12.125 in across the width
- Along 168 in: run each side (168 − 24) ÷ 2 = 72 in; 2 full tiles per side; cut 72 − 48.25 − 0.125 = 23.6 in. Field: 5 full tiles with 23.6 in cuts at both ends
- Across 144 in: run each side (144 − 12) ÷ 2 = 66 in; 5 full per side; cut 66 − 60.625 − 0.125 = 5.25 in. Field: 11 full rows with 5.25 in cuts at both walls
- Balanced alternative across the width: joint centred gives 10 full rows and 11.2 in cuts
Along the length the cuts are nearly full tiles, which is as good as it gets. Across the width a 5.25 in cut is acceptable but a 11.2 in cut looks better and is easier to make, so most installers would centre a joint across this room and a tile along it. Thirteen rows of seven pieces is 91 pieces to handle, which matches the floor tile calculator’s order of 91 tiles for this room.
A 9 × 7.5 ft bathroom in 12 × 12 tile, joint centred
3/16 in joint for a handmade-look ceramic.
- Pitch: 12.1875 in both ways
- Along 108 in: run each side (108 − 0.1875) ÷ 2 = 53.9 in; 4 full per side; cut 53.9 − 48.75 − 0.19 = 4.97 in. Field: 8 full tiles, cuts of 5 in at both walls
- Across 90 in: run each side 44.9 in; 3 full per side; cut 44.9 − 36.56 − 0.19 = 8.16 in. Field: 6 full rows, cuts of 8.2 in
- Balanced alternative along the length: tile centred gives 7 full tiles and 11.25 in cuts
Here the better choice differs by direction: centre a tile along the length (11.25 in cuts instead of 5 in) and a joint across the width (8.2 in instead of a 2 in sliver that tile-centred would give). The grid is set by two chalk lines, one for each direction, so mixing the two starts is normal.
Where to find your inputs
Room length and width. Measure at floor level at both ends of each wall and use the smaller figure; if the two differ by more than a joint width, the room is out of square and the cuts will taper.
Tile size. The nominal size on the box. Decide which way the long side runs and enter it as the tile length; the room length is the dimension it runs along.
Joint. The spacer size you will use: 1/16 in for rectified tile, 1/8 in for most floor tile, 3/16 in for handmade-look tile.
Smallest cut. Your own tolerance. Two inches is the practical floor; a third of a tile is the aesthetic one.
Common mistakes
- Starting at a wall because it is easier. The far wall gets whatever is left, and it is usually a sliver.
- Centring a tile out of habit. Half the time centring a joint gives the better cuts. Check both.
- Measuring one end of the room. Rooms are rarely square. Measure both ends and the diagonals.
- Ignoring the doorway. A full tile at the threshold often matters more than symmetry at the walls. Decide which wins before you snap lines.
- Forgetting the wall gap. Tile needs a joint’s width at the wall for movement; the cut tile is that much narrower.
- Treating this as the order quantity. Cut tiles consume whole tiles. Count the boxes on the floor tile calculator with waste added.
Questions people ask
- Should I start tiling from the centre of the room or from a wall?
- From the centre, almost always, so that the cut tiles at opposite walls are equal and the room looks symmetrical. Starting at a wall only works when the wall is straight and square and the cut at the far wall happens to be a good size, which you can check here before you decide.
- What is the difference between centring a tile and centring a joint?
- Centring a tile puts a whole tile in the middle of the room and the cuts at the walls are what is left over; centring a joint puts a grout line in the middle, which shifts every tile by half a pitch and changes the cut width by half a tile. One of the two nearly always gives a comfortable cut where the other gives a sliver.
- How narrow is too narrow for a cut tile?
- Installers avoid anything under about 2 inches, because it is hard to cut cleanly, it looks wrong next to a full tile, and it is a weak point at the wall. A cut of at least a third of a tile looks deliberate. The calculator takes your own minimum and warns when a layout falls below it.
- How many rows of 12 × 24 tile fit in a 10 ft wide room?
- With a 1/8 inch joint the pitch is 12.125 inches, so 120 inches holds 9 full rows (109.1 inches) with 10.9 inches left over. Centring a tile gives 9 full rows and two cuts of about 5.4 inches; centring a joint gives 8 full rows and two cuts of about 11.2 inches, which most people prefer.
- Does the layout change how many tiles I need?
- A little, and only at the walls. Each cut tile at a wall still consumes a whole tile unless the offcut can be reused on the opposite wall, which is why the floor tile calculator adds 10% for a straight layout. Use this page to choose the layout and that page to count the boxes.
- Why does the result talk about the room being square?
- Because a layout centred on a room that is 1/2 inch wider at one end than the other produces cuts that taper visibly along the wall. Measure both ends of each wall and the diagonals before you snap the lines; if the room is out of square, align the grid with the most visible wall and let the cuts taper along the wall under the cabinets or the bath.