Lumber & Framing calculators
Studs, plates, plywood, joists, decking and stairs.
- Wall Framing CalculatorStuds, plates, corners and openings
- Stair CalculatorRisers, treads, total run and stringer
- Deck Boards CalculatorBoards, joists, screws and hidden fasteners
- Plywood & Sheet CalculatorSheets of ply, OSB or subfloor
- Board Foot CalculatorBoard feet and cost for hardwood
- Siding CalculatorSquares and planks of lap siding
What is in this category
Four calculators for structural lumber and the sheet goods that go over it: wall framing, plywood and sheathing, deck boards and stairs.
Why everything is 16 or 24 inches
Framing spacing is not arbitrary. Sheet materials — plywood, OSB, drywall, subfloor — come in 4 ft widths, and 48 divides evenly by both 16 and 24. So every sheet edge lands on the middle of a framing member with nothing left over and nothing unsupported.
Sixteen inches on center is the default almost everywhere. Twenty-four — usually called advanced framing — uses about a third fewer studs and leaves more room for insulation, but generally needs 2x6 studs on load-bearing walls and 5/8 in. drywall on ceilings so it does not sag between framing.
Get the spacing right and the sheet goods calculation follows automatically. Get it wrong and you are cutting and blocking every sheet.
What catches people out with lumber
The layout count is not the order. A stud every 16 inches is the easy part. Every corner adds two studs, every door and window adds four, and then there are cripples above the headers and blocking wherever something has to be screwed to the wall later. On a real wall that is often close to double the layout number.
Nominal is not actual. A 2x4 measures 1-1/2 by 3-1/2 inches. A 2x10 is 1-1/2 by 9-1/4. Every framing calculation uses the actual dimension, and plate thickness at 1-1/2 in. is why studs get cut shorter than the wall is tall.
Lumber is graded loosely. Any bundle contains boards with a crown, a twist or a split end. Sighting down each one at the store and rejecting the bent ones takes ten minutes and is worth doing. Spare studs never go to waste on a job site — they become blocking and backing.
Stairs are the one place code is exact. Riser height, tread depth and the variation allowed between steps are all specified, because people climb stairs by rhythm rather than by looking. The stair calculator checks your numbers against those limits as it works them out.