Alcove Shelving Calculator
How much MDF and timber do you need for alcove shelves? Enter each alcove and the number of shelves, and get the frame under each shelf the way Wickes' guide builds it, every shelf top laid out on the sheet, and every frame piece cut from as few lengths as possible.
Last reviewed: 30 September 2026
Materials
Measure each alcove's width wall to wall, and the depth you want the shelves, at the height of the shelves.
How Much MDF and Timber for Alcove Shelves?
Wickes' guide builds each shelf as a timber frame screwed to the alcove walls, with a solid MDF top. So each shelf needs a top the width and depth of the alcove, two long pieces of timber for the back and front, and two short side pieces.
The usual sum is the shelf area plus 10% over the sheet area. On a full 2440 x 1220mm sheet it usually works: the default two alcoves need 1 sheet. On the smaller 1829 x 606mm sheet it can be well short, because two deep shelves will not fit side by side across it: the same shelves need 6 sheets, not 3. In the table below the sum is short on the small sheet in 2 of 5 jobs.
How the Plan Works
- The frame. Wickes: two long pieces cut to the width of the alcove, two short pieces to the depth, less the front and back pieces so they fit flush.
- The top. Wickes: one solid piece that forms the shelf top. The calculator makes it the full width and depth.
- Sheet layout. Tops cut from the sheet with straight cuts, turned round where that fits better, with a 3mm saw cut (our working).
- Timber. Frame pieces cut from lengths longest first, each into the length with least room left (our working).
What it does not do: shelf spacing, loads or wall fixings, which Wickes says to choose for your wall, or a front fascia strip.
Materials, With Sources
Every sheet and timber in the dropdowns has a Wickes product page.
| Material | Product page |
|---|---|
| MDF 18mm, 2440 x 1220mm | Wickes General Purpose MDF Sheet, 18 x 1220 x 2440mm |
| MDF 18mm, 1829 x 606mm | Wickes General Purpose MDF Sheet, 18 x 606 x 1829mm |
| PSE 18 x 44mm, 2.4m | Wickes PSE Whitewood Timber, 18 x 44 x 2400mm |
| PSE 18 x 44mm, 1.8m | Wickes Whitewood PSE Timber, 18 x 44mm x 1.8m |
The frame and top are from Wickes' alcove shelving guide. Which way the timber goes, the sheet layout and the saw cut are our own working.
Common Alcoves: Materials Needed
Generated from the calculator above, with 18 x 44mm timber in 2.4m lengths. Sheet cells are the layout, then the area sum.
| Job | 2440 x 1220 Sheets | 1829 x 606 Sheets | Timber Lengths |
|---|---|---|---|
| Two alcoves, 900 x 300mm, 4 shelves each | 1 (1) | 2 (3) | 8 (9) |
| Two alcoves, 1000 x 350mm, 3 shelves each | 1 (1) | 6 (3, short) | 7 (8) |
| Two alcoves, 1100 x 400mm, 4 shelves each | 2 (2) | 8 (4, short) | 11 (11) |
| One alcove, 800 x 280mm, 5 shelves | 1 (1) | 2 (2) | 5 (5) |
| One alcove, 1200 x 300mm, 3 shelves | 1 (1) | 2 (2) | 6 (5) |
Frequently Asked Questions
How much MDF do I need for alcove shelves?
The usual sum is the shelf area plus 10%, over the sheet area. On a full 2440 x 1220mm sheet that usually works: two alcoves 1000mm wide and 350mm deep with 3 shelves each need 1 sheet. But on the smaller 1829 x 606mm sheet, two 350mm deep shelves do not fit side by side across it, so the same shelves need 6 sheets where the area sum says 3. In the table below the sum is short on the small sheet in 2 of 5 jobs. This calculator lays every shelf top out on the sheet.
What timber goes under each shelf?
Wickes' guide builds a frame under each shelf: two long pieces cut to the width of the alcove for the back and front, and two short pieces for the sides, cut to the depth less the front and back pieces so they fit flush. With 18mm timber that is the depth less 36mm. The MDF top screws onto the frame.
How many lengths of timber do I need?
Two alcoves 1000mm wide with 3 shelves each need 7 lengths of 2.4m. Watch for pieces just over half a length: a 1200mm wide alcove needs 1200mm back and front pieces, and two of those plus a saw cut do not fit in a 2400mm length, so one alcove with 3 shelves needs 6 lengths where the length sum says 5.
Which way should the timber go?
The calculator takes the timber fixed flat to the wall, so its 18mm thickness comes off the depth at the front and back (our reading of Wickes' guide). If you fix it the other way, the sides get shorter by the timber's width instead.
Does it work out the shelf spacing or load?
No. Wickes says to allow for what goes on the shelves, with bigger gaps for books, and to use fixings to suit your wall. The calculator only works out the materials and the cutting.