Tiles & flooring· 3 min read
120 × 60 cm Tiles: Straight Lay or a One-Third Offset?
120 × 60 cm tiles in a 5 × 4 m room: how many you need straight, at 1/2, 1/3 and 1/4 offset, and why long tiles should be offset by a third at most.
120 × 60 cm tiles (about 48 × 24 in) turn a room into one calm surface with few joints. With a format this large, though, every pattern choice means whole tiles more or less — and a half offset also risks edges that will not sit flush.
The example
- Room 5,000 × 4,000 mm, i.e. 20 m².
- Tile 1,200 × 600 mm, long side along the 5 m wall, 2 mm joint.
- The area estimate is 28 tiles — in reality you need more.
Patterns compared, starting from the centre
| Layout | Whole | Cut | Total | +10 % reserve | Narrowest piece |
|---|---|---|---|---|---|
| Straight | 15 | 20 | 35 | 39 | 494 mm |
| 1/2 offset | 18 | 20 | 38 | 42 | 95 mm |
| 1/3 offset | 15 | 20 | 35 | 39 | 295 mm |
| 1/4 offset | 16 | 21 | 37 | 41 | 95 mm |
A half offset costs 3 extra tiles here and leaves pieces only 95 mm wide at the row ends. A third offset needs the same count as a straight lay, and its narrowest piece is 295 mm. Starting from a corner, all four patterns came to 35 tiles with a narrowest strip of 192 mm.
Corner or centre?
Laid straight from a corner, one side ends with a 192 mm strip and the other with 388 mm, while the opposite walls get whole tiles. From the centre the strips are symmetrical: 696 mm at the short walls and 494 mm at the long ones. With a large format symmetry shows more than with small tiles, because every strip is wide and easy to see.
An offset adds more cut pieces at the row ends. With a centred third offset they are 295, 696 and 1,097 mm wide; with a half offset 95 and 696 mm. Those 95 mm slivers are why the half offset does worse in this room — and with a large format they are awkward to cut and to bed.
Why not a half offset
No tile is perfectly flat — long tiles bow slightly along their length. With a half offset the middle of one tile meets the ends of its neighbours, creating lippage: a step you feel underfoot and see in raking light.
That is why the US standard ANSI A108.02 limits the offset to a maximum of 33 % when the side being offset is longer than 15 in (about 38 cm), unless the tile manufacturer specifies otherwise. A larger offset requires the specifier and owner to approve a mock-up and the resulting lippage. The Ceramic Tile Foundation adds that many manufacturers now recommend a 33 % offset outright. Whatever standard applies where you live, the tile’s own data sheet has the final say.
Tiles & flooringOpen the 1/3 offset exampleWorking it out for your room
- 1Enter the room and tile sizes the way you want the tile turned — long side along the room width.
- 2Set the joint from the tile’s data sheet.
- 3Choose the offset layout and switch between 1/2, 1/3 and 1/4. Watch the tile count and the thin-strip warning.
- 4Switch the start between corner and centre and pick the combination with a sensible count and no piece narrower than about a third of a tile.
Workshop tips
- A 1/3 offset on a 1,200 mm tile is about 400 mm — mark it on a gauge stick rather than measuring every row.
- Dry-lay at least the first three rows before bonding. You will see where the cuts fall and whether neighbouring edges sit flush.
- If the room is long and narrow, also try the tiles turned 90° in the calculator — the count and the edge strips both change.
- Large tiles are awkward to carry and can crack when cut. Don’t skimp on the reserve and keep at least one tile for repairs.
With large formats, substrate flatness, adhesive and trowelling technique decide the result. Follow the tile and adhesive manufacturers’ data sheets — the calculator only counts tiles and cuts.