Carpentry calculators

Lay out stairs and framing from your measurements, checked against the code before you cut.

Risers, treads, stringer length and a cut list from the total rise, checked against the IRC or IBC stair rules.

Posts, pickets, rails and post-hole concrete for a wood fence, from the length of each run and the gates.

Deck boards, linear feet, screws or hidden clips for a deck of any size, straight or diagonal.

Studs, plates and precut stud length for any set of walls, with corners, intersections, doors and windows, and the cost.

Header size and jack studs for a door, window or garage door in a bearing wall, from IRC Table R602.7(1).

Sheets of plywood or OSB for walls, floors or any area, with waste, weight per sheet and the cost.

Maximum floor and ceiling joist spans by species, grade, size and spacing, worked from the AWC 2024 span tables and design values.

Maximum rafter span for roof live or snow load, by species, grade, size and spacing, from the AWC 2024 span tables.

Maximum deck joist span and overhang by species, size and spacing, from the AWC DCA 6 tables, with a check of your span.

Maximum deck beam span for every beam size by the joist span it carries, and the posts each beam needs, from AWC DCA 6.

Footing size and thickness, maximum 6x6 post height and concrete for deck posts, from AWC DCA 6 Table 4.

How many balusters a railing needs and the exact gap between them, kept under the IRC's 4 inch sphere rule.

Board feet for any list of lumber, with price, plus Doyle, Scribner and International log scales.

Before you cut

Measure the finished heights. Stairs are laid out from finished floor to finished floor. Flooring added later changes the top and bottom steps.
Check the code. Residential stairs follow IRC R311.7; commercial stairs follow IBC Section 1011. The rules differ, and decks follow the IRC.
Cut one, test it, copy it. A test stringer in place catches a sloping floor or a bad measurement before the rest of the lumber is cut.