Framing & carpentry calculators

Counting lumber for a framing job

These calculators cover the lumber side of a framing job: studs, plates and header stock for walls; sheets of plywood or OSB for walls, roofs and subfloors; board feet for a lumber order; and deck boards with their screws and joists. Each one shows its formula and a worked example, so you can follow the count by hand.

A common shortcut for walls framed at 16 inches on center is one stud per linear foot of wall, which roughly covers corners, openings and a few culls; the wall framing calculator counts them properly instead. Sheathing usually needs 5 to 10% extra for cuts around openings and at gable ends, and deck boards about 10%, more if you run them on a diagonal.

A deck uses three of these together: the deck board calculator for boards, joists and fasteners, the board foot calculator to price the framing lumber, and the sheathing calculator for any subfloor. For walls, the studs per wall chart lists stud counts for common wall lengths alongside the IRC stud spacing table.

Structural sizing, such as header spans, joist spans, beam sizes and deck ledger attachment, depends on loads, species and grade, and on the building code your town has adopted. These tools count material; they do not size members. Pull a permit and, where spans are long or loads are unusual, have an engineer or your lumber yard’s design desk check the framing.

How each calculator is specified, tested and corrected is described on our methodology page.