Tile Backer Board Calculator
How many tile backer boards do you need? The area rule is a guess: usually a board over, now and then a board short, because on a stud wall every vertical joint has to land on a stud. Enter your walls or floor and get every board laid out the way NoMorePly's guide says, with the joints on the studs, offcuts reused, and the screws and noggins counted.
Last reviewed: 30 September 2026
Surface
For a wall, enter its length and height, measured from a stud at one end. For a floor, its length and width. NoMorePly says studs should be at most 600mm centres. Leave the extra allowance at 0%: the plan already counts every cut.
How Many Tile Backer Boards Do I Need?
The usual answer is the area plus 10%, divided by the board area. It can go either way. For a shower of 900, 1200 and 900mm walls tiled to 2400mm it gives 9 of NoMorePly's 1200 × 800mm boards, and with studs at 600mm 8 will do. For a recess of 900, 1700 and 900mm walls at 2200mm high it gives 9, but the walls need 10. In the table below the area rule is over on 3 of 6 walls and short on 1.
That is because the boards have to be fixed to something. NoMorePly's guide says studs at most 600mm centres, with cross noggins on the board joints, so every vertical joint lands on a stud and the cuts fall where the studs are. A 900mm wall takes a cut piece in every row. So this calculator lays each board out with the joints on the studs, staggers the rows by one stud, and reuses the offcuts where they fit.
How the Layout Works
- Joints on studs. NoMorePly: "Studs to be max 600mm centres with cross noggins on board joints". Vertical joints only at whole stud centres from the end of the wall.
- Joints staggered. NoMorePly: "Stagger the boards where possible". Rows are offset by one stud on walls and by half a board on floors (our choice).
- Long side horizontal on walls. Our choice: rows of 800mm boards up the wall.
- Offcuts reused. Pieces end to end, strips side by side, turned 90 degrees where that fits an offcut (our rule), with 3mm lost at each cut. A piece against the end of a wall, the floor or the ceiling may come out up to 3mm short on that side, which the adhesive fills (our rule). No piece under 100mm where it can be avoided (our rule).
- Screws per board. NoMorePly: about 9 × 38mm per board on stud walls, 8 × 25mm per board on timber floors.
What it does not do: solid walls (dot and dab), windows, niches, pipes, tanking or adhesive. Enter the wall round a window as smaller walls.
Boards, With Sources
Both boards are NoMorePly, the brand whose installation guide the rules come from, and both have a Wickes product page.
| Use | Board | Product page |
|---|---|---|
| Floors | 1200 × 600 × 6mm, 8 screws a board | NoMorePly Pre-Primed Fibre Cement Board, 6 x 600 x 1200mm |
| Stud walls | 1200 × 800 × 12mm, 9 screws a board | NoMorePly Fibre Cement Board, 12 x 800 x 1200mm |
The rules are from NoMorePly's installation guide, hosted by Wickes. Laying wall boards long side horizontal, the stagger distances, the shortest piece, the cut allowance and the way offcuts are reused are our own working.
Common Jobs: Boards Needed
Generated from the calculator above, with studs at 600mm and nothing added. The area rule is the area plus 10%, over the board area.
| Job | Board | Boards | Area Rule | Screws | Noggins |
|---|---|---|---|---|---|
| Shower, 900 + 1200 + 900mm walls, 2400mm high | 12mm, 1200 x 800 | 8 | 9 | 72 | 6.0m |
| Shower, 900 + 1500 + 900mm walls, 2200mm high | 12mm, 1200 x 800 | 9 | 9 | 81 | 6.6m |
| Shower, 800 + 1400 + 800mm walls, 2000mm high | 12mm, 1200 x 800 | 7 | 7 | 63 | 6.0m |
| Recess, 900 + 1700 + 900mm walls, 2200mm high | 12mm, 1200 x 800 | 10 | 9 (short) | 90 | 7.0m |
| Bath end and back, 700 + 1700mm walls, 1200mm high | 12mm, 1200 x 800 | 3 | 4 | 27 | 2.4m |
| One wall, 2400 x 2400mm | 12mm, 1200 x 800 | 6 | 7 | 54 | 4.8m |
| Floor, 2.0 x 1.5m | 6mm, 1200 x 600 | 5 | 5 | 40 | - |
| Floor, 2.5 x 1.8m | 6mm, 1200 x 600 | 7 | 7 | 56 | - |
| Floor, 3.0 x 2.4m | 6mm, 1200 x 600 | 10 | 11 | 80 | - |
Frequently Asked Questions
How many tile backer boards do I need?
The usual sum is the area plus 10%, divided by the board area. It is a guess, and it cannot tell you which way it is wrong. For a shower of 900, 1200 and 900mm walls tiled to 2400mm it gives 9 of NoMorePly's 1200 × 800mm boards, and with studs at 600mm 8 will do. For a recess of 900, 1700 and 900mm walls at 2200mm high it gives 9, but the walls need 10, because the vertical joints have to land on a stud and the cuts fall where the studs are. This calculator lays every board out with the joints on the studs and reuses offcuts where they fit. In the table below the area rule is over on 3 of 6 walls and short on 1.
Where do the joints have to go on a stud wall?
NoMorePly's guide says studs should be at most 600mm centres, with cross noggins on the board joints. So a vertical joint lands on a stud and a horizontal joint on a noggin. The calculator only puts a vertical joint at a whole number of stud centres from the end of the wall, and staggers the rows by one stud. It counts a row of noggins at every horizontal joint: 6 rows, 6.0m in all, for the default shower. Stud centres change where the cuts fall: with studs at 400mm the same shower needs 9 boards, against 8 at 600mm.
How many screws do I need?
NoMorePly's guide says approximately 9 × 38mm screws per board on stud walls, and 8 × 25mm screws per board when over boarding a timber floor, and that 50 screws are enough for 6 floor boards. The calculator uses those per-board figures and the boards you buy: 72 for the default shower.
Which board goes on walls and which on floors?
NoMorePly's guide uses its 12mm board (1200 × 800mm) for stud walls and solid walls, and its 6mm PrePrimed board (1200 × 600mm) for over boarding timber and concrete floors. Both are on Wickes product pages, listed below.
Do the joints need taping?
NoMorePly says to run a bead of its MEGA Strength adhesive round the edge of each board before offering up the next, which reinforces and waterproofs the joint so it does not need taping. It also says to stagger the boards where possible. The calculator does not count the adhesive.
What about floors?
Choose floor and the calculator lays 6mm boards in staggered rows, both ways round, and keeps the way that needs fewer. On a plain rectangle the area rule is usually close or a board over: a 2.0 × 1.5m floor needs 5, and the area rule gives 5. In the table below it is over on 1 of 3 floors.
What does it not cover?
Solid walls, which NoMorePly boards with dot and dab adhesive and at least 4 mechanical fixings per board, windows, niches, pipes, tanking and the adhesive. Enter the area round a window as smaller walls, and use the extra allowance for the rest.