How to read the stud chart
Find the wall length in the first column and read across to the spacing you are framing at. The count is the number of common studs for a straight run: one at each spacing plus one to close the far end. The plate column gives lineal feet of plate stock for one bottom plate and a doubled top plate.
Worked example: a 20 ft exterior wall at 16 in OC needs 16 common studs and 60 lineal feet of plate. With a three-stud corner at each end (+2 each) and one window (+2 king, +2 jack), the order is 24 studs, plus cripples and any blocking.
The rule behind the count
Studs = length ÷ spacing, rounded up, plus one. Rounding up covers the last partial bay, and the extra stud closes the end of the wall. Working in inches avoids errors: a 10 ft wall is 120 in, 120 ÷ 16 = 7.5, round up to 8, plus 1 = 9. Layout starts from one end so that sheet edges land on stud centres at 4 ft, 8 ft and so on.
Spacing limits in the IRC
IRC 2021 Table R602.3(5) sets the maximum stud spacing by stud size, wall height and what the wall carries. The third table on this page reproduces it. In short, 2×4 bearing walls up to 10 ft tall may be framed at 24 in OC when they carry only a roof and ceiling, but need 16 in OC when they also carry a floor; 2×6 bearing walls can stay at 24 in OC with one floor above. Engineered designs, high-wind and seismic regions, and taller walls follow other rules.
Common stud count mistakes
- Dividing feet by inches (10 ÷ 16) instead of converting the length to inches first.
- Forgetting the extra studs at corners, intersections and every opening.
- Ordering plates for a single top plate when the design calls for a double.
- Leaving out backing for cabinets, grab bars and drywall edges at inside corners.
Spacing limits are from the 2021 International Residential Code. Local amendments apply; confirm with your building department.