How it works
The formula
layout studs = wall length × 12 ÷ spacing, rounded up, + 1
each opening: at each end, the king studs from IRC Table R602.7.5 + 1 jack
plates = 3 × wall length (a double top plate and a bottom plate)
each opening: at each end, the king studs from IRC Table R602.7.5 + 1 jack
plates = 3 × wall length (a double top plate and a bottom plate)
- Stud spacing follows 2021 IRC Table R602.3(5): 2×4 bearing walls at up to 24 in when they carry only the roof and ceiling, 16 in under a floor plus the roof.
- King studs at each end of a header in an exterior wall, from Table R602.7.5 by header span, for up to 115 mph in Exposure B (and, in brackets, under 140 mph in B or 130 mph in C): 4 ft: 1 (1); 6 ft: 1 (2); 8 ft: 1 (2); 10 ft: 2 (3); 12 ft: 2 (3); 14 ft: 2 (3); 16 ft: 2 (4); 18 ft: 2 (4). A wide opening may need 2 or 3 jack studs under each end of the header: size headers from Table R602.7(1).
- The double top plate is R602.3.2. A 2-stud corner with drywall clips is an advanced-framing option (Insulation Institute); the code doesn't set a corner stud count.
- Cripple studs above and below windows aren't counted; they're usually cut from the offcuts and a few extra studs.
Layout studs by wall length
| Wall | 16 in on center | 24 in on center |
|---|---|---|
| 8 ft | 7 | 5 |
| 12 ft | 10 | 7 |
| 16 ft | 13 | 9 |
| 20 ft | 16 | 11 |
| 24 ft | 19 | 13 |
| 30 ft | 24 | 16 |
| 40 ft | 31 | 21 |
Before openings and corners.
Questions people ask
How many studs for a 24 ft wall?
At 16 in on center, 19 layout studs; at 24 in, 13. Add king and jack studs at each window and door and extra studs at corners: with two 3 ft openings and one corner, 29 at 16 in.
What are king and jack studs?
A king stud runs full height beside an opening; a jack stud is fastened to it and holds up the header. The code's table sets how many full-height studs each end of a header needs.
16 or 24 inches on center?
Most walls are framed at 16 in. The code allows 24 in for 2×4 bearing walls that carry only the roof and ceiling; 2×6 walls at 24 in are common in advanced framing, leaving more room for insulation.