Stud Wall Calculator
How many studs do you need for a stud wall? Enter the wall and any doors and get a real layout: studs at your centres, king and trimmer studs, headers and cripples round each door, noggins, plates, and a check that every plasterboard joint lands on a timber. A cutting plan reuses offcuts. For non-load-bearing partitions only.
Last reviewed: 30 September 2026
Wall
For non-load-bearing partition walls only. Studs run between a head plate and a sole plate.
Timber
C16 CLS, each size and length has a Wickes product page below. Stock varies by merchant, so check before ordering.
British Gypsum's recommended centres for timber studs: 600mm for 1200mm-wide 12.5mm or 15mm board, 450mm for 900mm-wide. Sheets go up vertically, so their edges run up the wall.
5% is enough here because the cutting plan already reuses offcuts, so a bigger figure would count them twice. It is for splits, bad cuts and bowed lengths.
Doors
For lining and clearance. Homebuilding gives an opening of around 825 x 2046mm for a 762 x 1981mm door, which is +63mm and +65mm.
How Many Studs Do I Need for a Stud Wall?
The usual answer is the wall length divided by the stud centres, plus one, with four studs added per door. For a 3.6m wall at 600mm centres that sum gives 7 studs. It says nothing about where the studs actually go, and it cannot tell you whether the plasterboard joints will land on timber.
So this calculator lays the wall out. It sets an end stud each side and common studs at your centres measured from the start of the wall, frames each door, checks every sheet joint, puts noggins between the studs, and packs every piece into timber lengths so short pieces come out of offcuts. For the same wall with one door it comes to 10 studs, 5 noggins and 4 plate pieces, 15 lengths of 2.4m timber with 5% spare.
What This Calculator Is For, and What It Is Not
It is for non-load-bearing timber stud partitions. A load-bearing wall carries the structure above it and needs a proper design. We do not give load or Building Regulations advice, and this is not a structural check. If you are unsure whether a wall is load-bearing, ask a structural engineer or your local building control before you touch it.
How the Layout Works
- Studs are at your centres from the start of the wall. An end stud sits flush at each end, and common studs go at 1 × centres, 2 × centres and so on. Because 600mm and 400mm both divide the 1200mm sheet width, and 450mm divides 900mm, every sheet joint lands on a stud centre.
- Every sheet joint is checked at your sheet width (1200mm or 900mm). A joint counts as supported if a stud centre is within 10mm of it. If not, an extra stud is added. Above a door the support is a cripple stud.
- Each door gets a king stud each side, a trimmer (jack) stud inside it, a header, and cripple studs above the header. The sole plate is cut away across the opening. Common studs that would clash with the door frame are dropped.
- Noggins go between full-height studs, midway up a standard wall. On a wall taller than 2400mm there is one at the 2400mm sheet joint, and rows are added so no gap is over 1350mm (TradeCalculator quotes the same figure).
- Long plates are joined with the head plate and sole plate joints kept apart.
- Offcuts are reused. All pieces are packed into lengths together, longest first.
Stud Centres and Plasterboard
British Gypsum's Site Book (2013 revision), in its timber stud partition table for Gyproc WallBoard, recommends stud centres of 600mm for 1200mm-wide 12.5mm and 15mm board and 450mm for 900mm-wide board. Its tiling notes say 400mm centres for 12.5mm board on a wall that will be tiled. It lists no 9.5mm board for timber stud partitions. Some DIY guides, such as Homebuilding, give 400mm for 9.5mm board, so the dropdown offers 400mm too, and you can enter your own centres.
Pick your sheet width as well. A centre spacing that does not divide the sheet width gets extra studs under the sheet joints, and the results say how many. On a 3.6m wall with 900mm-wide boards, 450mm centres need 0 extra studs and 600mm centres need 2. On a 3.6m wall with 1200mm boards, 450mm centres need 2.
Taller than a sheet? Plasterboard is 2400mm tall, so a wall over 2400mm has a horizontal joint. The calculator puts a noggin there so both sheets can be screwed to it. A 2700mm wall gets 2 rows of noggins, at 1200mm and 2400mm.
Framing a Door Opening
Following Screwfix's stud wall guide: king studs on either side, trimmer studs attached to them to form the frame sides, a header across the top, a cripple stud above the header, and the bottom plate cut away across the opening. Homebuilding says doubling up the studs is not essential but is a good idea for heavy or fire doors, so it is a switch here.
The opening is the door plus a little for the lining and clearance. For a 1981 × 762mm door Homebuilding gives around 825 × 2046mm, which is what we use by default (825 × 2046mm). Pick your door from the dropdown, or enter a custom width and height, and set how far the opening starts from the wall end.
Timber Sizes We Use, With Sources
Studs are typically 38 × 63mm or 38 × 89mm (Screwfix). Every size and length in the calculator has a Wickes product page, all C16 graded and sold singly. No product page means no dropdown entry. Stock varies by merchant, so check before ordering.
| Size | Length | Product page |
|---|---|---|
| 38 x 63mm | 2.4m | Wickes Studwork CLS Timber, 38 x 63 x 2400mm |
| 38 x 63mm | 3.0m | Wickes Studwork CLS Timber, 38 x 63 x 3000mm |
| 38 x 89mm | 2.4m | Wickes Studwork CLS Timber, 38 x 89 x 2400mm |
| 38 x 89mm | 3.0m | Wickes Studwork CLS Timber, 38 x 89 x 3000mm |
Common Wall Sizes: Studs and Timber Needed
Generated from the calculator above. Each wall is 2.4m high, uses 38 × 63mm timber in 2.4m lengths, and has 5% waste. The last column has one 762mm door 600mm from the start.
| Wall | Studs at 600 | Studs at 400 | Noggins at 600 | Lengths at 600 | Lengths, with a door |
|---|---|---|---|---|---|
| 2.4m × 2.4m | 5 | 7 | 4 | 9 | 11 |
| 3m × 2.4m | 6 | 9 | 5 | 11 | 13 |
| 3.6m × 2.4m | 7 | 10 | 6 | 13 | 15 |
| 4.2m × 2.4m | 8 | 12 | 7 | 15 | 16 |
| 4.8m × 2.4m | 9 | 13 | 8 | 16 | 18 |
| 6m × 2.4m | 11 | 16 | 10 | 20 | 23 |
Use the calculator for your own wall. A door, a taller ceiling or a different centre spacing changes the answer more than you would expect. Building a bathroom or shower wall? Our shower panel calculator lays out the wall panels that go on it.
Frequently Asked Questions
How many studs do I need for a stud wall?
The usual sum is wall length divided by the centres, plus one. For a 3.6m wall at 600mm centres that gives 7. It ignores the door. A door needs a king stud and a trimmer stud each side, a header and cripple studs above it, and the common studs that fall in the way come out. This calculator lays the whole wall out. With one 762mm door it comes to 10 studs, 5 noggins and 4 plate pieces, and 15 lengths of 2.4m timber once 5% spare is added.
Should studs be at 400mm or 600mm centres?
For standard 1200mm-wide plasterboard, 600mm. British Gypsum's Site Book gives recommended stud centres for timber studs of 600mm for 1200mm-wide 12.5mm and 15mm Gyproc WallBoard, and 450mm for 900mm-wide boards. It lists timber stud partitions for 12.5mm and 15mm board only. It says 400mm for 12.5mm board where the wall will be tiled, because tiles add weight. Some DIY guides give 400mm for 9.5mm board, so it is offered as an option. Both 600mm and 400mm divide the 1200mm sheet width, so each sheet edge lands on a stud. The calculator checks every sheet joint and adds an extra stud if one is missing. On a 3.6m wall with 900mm-wide boards, 450mm centres need 0 extra studs and 600mm centres need 2.
How do you frame a door opening in a stud wall?
A king stud each side, full height. A trimmer (jack) stud inside each king, running from the floor to the header. A header across the top of the opening, and cripple studs above it up to the head plate. The bottom plate is cut away across the opening. For a 1981 × 762mm door Homebuilding gives an opening of around 825 × 2046mm, which is 63mm wider and 65mm taller than the door, and that is the default here. Doubling up the studs is not essential, so you can turn it off.
Where do the noggins go?
Between the studs, midway up the wall for a standard-height wall, and staggered so you can screw through each stud. Where two sheets meet, put a noggin behind the joint so both can be screwed to it. Sheets are 2400mm tall, so a wall over 2400mm has a horizontal joint there. This calculator puts a noggin at 2400mm on taller walls and adds rows so no gap between rows or plates is over 1350mm. A 2700mm wall gets 2 rows, at 1200mm and 2400mm.
What size timber should I use for a stud wall?
Studs are typically 38 × 63mm or 38 × 89mm. The thicker one gives a deeper wall for cables or insulation. Both come in 2.4m and 3.0m lengths at Wickes, as C16 graded CLS sold singly. A stud is the wall height minus two plate thicknesses, so a 2.4m wall needs 2324mm studs, and a taller wall may need the 3.0m length. Stock varies by merchant, so check before ordering.
Does the calculator reuse offcuts?
Yes. Every piece is cut from your stock length, longest first, so noggins and cripples come out of the offcuts of longer pieces. A 2324mm stud from a 2.4m length leaves only 76mm, which is no use, but on 3.0m timber each stud leaves 676mm for a noggin. The ranking under the results compares the two lengths for your wall.
Is this for load-bearing walls?
No. This is for non-load-bearing timber partition walls only. A load-bearing wall carries the structure above it and needs a proper design. We do not give load or Building Regulations advice. If you are unsure whether a wall is load-bearing, ask a structural engineer or your local building control before you touch it.