Wall stud calculator: how many studs do I need?
Count the studs on layout first, then add the extras, as this wall stud calculator does:
- Layout: wall length ÷ spacing, rounded up, + 1. A 12 ft (144 in) wall at 16 in: 144 ÷ 16 = 9, + 1 = 10.
- Corners: +2 each for a three-stud corner, +1 for a two-stud (California) corner.
- Openings: +4 each, two full-height kings and two jacks under the header. The layout studs inside the opening become cripples.
- Waste: add 5–10% for bowed or split studs.
For a full material list with plates, headers and sheathing, use the wall framing calculator on the home page.
Stud spacing: 16, 19.2 or 24 inches
Stud spacing is set by the IRC by stud size and load: 2x4 bearing studs may be 24 in apart when they carry only a roof and ceiling, but 16 in when they also carry a floor[1].
| Stud | Roof + ceiling | + one floor | + two floors |
|---|---|---|---|
| 2x4 | 24 in | 16 in | not allowed |
| 2x6 | 24 in | 24 in | 16 in |
Nonbearing 2x4 walls may be up to 14 ft tall at 24 in. The 19.2 in spacing (five studs per 8 ft) suits 8 ft sheet goods and is marked on most tapes with a small black diamond, as on the strip at the top of this page. Advanced framing uses 2x6 at 24 in with two-stud corners[2].
Stud layout marks
Pull the tape from the end of the plate and mark 3/4 in short of each multiple of the spacing, so the stud's centre lands on 16, 32, 48 … and 4 ft sheets break on the middle of a stud. For a 12 ft wall at 16 in the left-edge marks are: 0″, 15-1/4″, 31-1/4″, 47-1/4″, 63-1/4″, 79-1/4″, 95-1/4″, 111-1/4″, 127-1/4″, 142-1/2″. The last stud goes flush at the far end.
- Lay out the top and bottom plates together, side by side, and square the marks across both.
- Mark an X on the side of the line where the stud goes.
- Openings: mark king and jack studs from the centre of the opening, then keep the cripples on layout.
Stud length
Stud length is the wall height minus the plates. With a bottom plate and a double top plate, each 1-1/2 in thick[3], an 8 ft 1-1/8 in wall needs 92-5/8 in studs, the common precut length for 8 ft ceilings. A 9 ft wall works out to 104-5/8 in. Sheathing and drywall take the rest of the material list; see the drywall calculator, and the lumber calculator to total the order.
Frequently asked questions
How do I use the stud calculator for wall openings?
Enter the wall length and spacing, then the number of openings: each adds two king and two jack studs. For headers, plates and cripples, use the full framing calculator.
How many studs do I need for a 10 ft wall?
At 16 in centres, 120 ÷ 16 = 7.5, rounded up to 8, plus 1: 9 studs on layout, before corners and openings.
How many studs per foot of wall?
At 16 in centres the layout alone is 3/4 stud per foot plus one; with corners, openings and waste a typical wall comes close to one stud per foot.
Should studs be 16 or 24 inches apart?
Both are allowed for many walls. 2x4 bearing walls that carry a floor must be at 16 in under the IRC; 2x6 walls can usually be at 24 in.
Where is the first stud mark at 16 inches?
At 15-1/4 in from the end of the plate, so the stud is centred on 16 in.