Wall framing calculator

Stud calculator: how the studs are counted

Studs are laid out from the wall's start, one every 16 or 24 inches on center, so sheathing and drywall edges land on them, with one more at the far end when the length isn't a whole number of spaces. A 12 foot wall at 16 inches is 9 spaces and 10 studs. An outside corner takes three studs by the usual method, the third backing the drywall inside; the advanced-framing corner uses two and carries the drywall on clips.

Each opening is framed out from its rough opening: jack studs under each end of the header, then the full-height king studs the header is nailed to. Layout studs that would fall in that framing are left out, and those inside the rough opening become cripples, above the header and, for a window, below the rough sill, so the layout carries on across the opening. The stud length is the wall height less the plates: an 8 foot 1 1/8 inch wall with a double top plate takes 92 5/8 inch studs.

Header size calculator: what the IRC tables say

Headers in exterior bearing walls come from IRC Table R602.7(1), and in interior bearing walls from Table R602.7(2). Each gives the longest opening a header of two, three or four 2x members (or one, between flat plates) may span, by what the wall carries, the building's width across the ridge and, outside, the ground snow load, with the number of jack studs each end needs. The tables are the same in the 2021 and 2024 editions. Widths between the columns are interpolated, as footnote c permits; snow loads round up to the next column, and under 30 psf use 30 where the roof live load is 20 psf or less. Where cripples bear on top of a 2x8, 2x10 or 2x12 header, its span is 0.70 of the table, because nothing braces its top edge. King studs in exterior walls follow Table R602.7.5, by the header's span and the design wind speed. A nonbearing partition needs no load-bearing header: a flat 2x does for an opening up to 8 feet with the plate within 24 inches above it.

Studs are checked against Table R602.3(5): 2x4 studs carrying a roof only go 24 inches on center, carrying a floor as well 16 inches, and can't carry two floors; bearing studs stop at 10 feet between supports, and partition studs at 14 feet for a 2x4 and 20 for a 2x6. Walls over 10 feet tall get a row of fireblocking every 10 feet (R302.11).

What the calculator will not do

The tables are for No. 2 Douglas fir-larch, hem-fir, Southern pine and spruce-pine-fir. An opening wider than any header in the table spans, a building wider than 36 feet, a ground snow load over 70 psf or a stud taller than the table allows needs an engineered header or stud (LVL, glulam, steel), so the calculator refuses it rather than guess. Wall bracing, hold-downs, sheathing and nailing schedules are not worked out here. Check your local code: jurisdictions adopt different editions and amend them, and your building department sets the snow load and wind speed.

The board foot calculator prices the lumber list, the 2x4 actual size page shows why a 2x4 is 3 1/2 inches wide, and the deck calculator and stair calculator do the rest of the framing.