Framing calculator

How the wall framing calculator counts lumber

A wall framing calculator counts studs on layout first, then adds what openings and corners need. It follows the order a framer lays out a plate:

1. Layout studs. One stud at each end and one every 16 or 24 in between: wall length ÷ spacing, rounded up, plus one.
2. Openings. Layout studs that land inside a rough opening are not full studs; they become cripples above the header and below the sill. Each opening gets two full-height king studs and two jack (trimmer) studs under the header.
3. Corners and intersections. A three-stud corner adds two studs, a two-stud (California) corner adds one; a partition backing adds two.
4. Plates. A bottom plate and a double top plate make three times the wall length.
5. Waste. The stud and plate totals get your waste allowance; jacks and cripples come from offcuts.

Studs are listed at the length that fits between three 1-1/2 in plates: for an 8 ft 1-1/8 in wall that is 92-5/8 in, the common precut stud length for an 8 ft ceiling with a double top plate.

Stud spacing and plates under the IRC

Stud spacing depends on stud size and what the wall carries; IRC Table R602.3(5) sets the limits^[1]. For bearing walls up to 10 ft tall:

• The top plate is doubled, overlapped at corners and bearing-wall intersections, with end joints offset at least 24 in. A single top plate is allowed when rafters or joists sit within 1 in of the studs and the plate is tied at joints^[1].
• Advanced framing, from the US DOE Building America program, uses 2x6 studs at 24 in, two-stud corners, single top plates and single headers on interior walls to save lumber and add insulation^[2]. Set spacing to 24 in, corners to 1 and plates to single to model it.
• Code editions and amendments vary by state and city; confirm with your building department^[5].

Header size calculator: length and depth

A header size calculator answers two questions: length, which is the rough opening plus one jack stud on each side (a 38 in opening takes a 41 in header), and depth, which comes from IRC Tables R602.7(1) to R602.7(3) by span, building width and load^[1]. This tool lists the lengths and lets you pick the depth from those tables. Nonbearing walls need no structural header; a single flat 2x4 can bridge openings up to 8 ft.

The rough opening is the unit size plus the allowance in the installation instructions. JELD-WEN, for example, wants a prehung exterior door frame 1 in narrower and 3/4 in shorter than the opening^[3]. Window makers publish their own minimums, so read the sheet for your unit before you frame.

All framing calculators

Each tool shows its formula and works in feet-inches or metric. Lumber sizes follow the American Softwood Lumber Standard^[4].

Stairs

• Stair calculatorRisers, treads, run and a code check for the US, UK, Canada and Australia.
• Stair stringer calculatorFraming-square settings, drop, throat, length and layout marks.
• Stair rise and run calculatorFit a stair into a fixed height and floor space.
• Stair calculator with landingL, U and straight stairs split into two flights.
• Deck stair calculatorDeck height to steps, 2x12 stringers and tread boards.
• Concrete stair calculatorPoured steps: layout and cubic yards.
• Spiral staircase calculatorDegrees per tread, walkline depth, headroom.
• Stair codeIRC riser, tread, width, headroom and rail rules.
• Baluster spacing calculatorEven gaps under the 4 in or 100 mm sphere.
• Stair tread calculatorTread and riser board sizes for a closed stair.
• Stair nosingCode projection, radius and depth.
• Handrail heightIRC, UK, Canada and Australia heights.

Lumber

• Board foot calculatorBoard feet for one board or a cut list, with cost.
• Lumber calculatorA lumber list by nominal size with actual sizes.
• Linear feet calculatorAdd up lengths or cover an area with boards.
• Lumber weight calculatorWeight of dry lumber by species and size.
• Feet and inches calculatorAdd, subtract, multiply and divide tape lengths.
• Decimal to fraction inchesNearest 1/16, 1/32 or 1/64 inch.
• Lumber dimensionsActual sizes of 2x4 to 2x12.
• Log board foot calculatorDoyle and International log rules.

Roofs

• Roof pitch calculatorPitch, degrees, percent and the roofing each pitch allows.
• Rafter calculatorCommon rafter length, overhang and birdsmouth.
• Roof calculatorRoof area, squares, bundles and trim.
• Hip roof calculatorHip, common and jack rafter lengths.
• Gambrel roof calculatorBarn-roof heights, rafters and gusset angles.
• Shed roof pitch calculatorLean-to pitch from two wall heights.
• Metal roof calculatorPanel count, panel length and trim.
• Roof truss calculatorTruss count, chords and webs.
• Rafter span chartMaximum rafter span by size, snow load and ceiling.
• 4/12 roof pitchDegrees, multiplier and roofing at 4/12 and up.
• How to measure roof pitchFive ways, with a degrees chart.

Walls and floors

• Stud calculatorStuds per wall and the layout marks on your tape.
• Joist span calculatorMaximum joist span by species, grade and spacing.
• Drywall calculatorSheets, screws, mud and tape for a room.
• Plywood calculatorSheets for subfloors, walls and roofs.
• Door rough openingOpening, header and jacks for a door.
• Window rough openingOpening, sill and header for a window.

Siding

• Siding calculatorSquares, lap boards, starter, corners and J-channel.
• Board and batten calculatorBoards and battens for a wall.

Trim

• Baseboard calculatorBaseboard and casing for a room.
• Crown molding calculatorMiter and bevel angles, length to buy.
• Wainscoting calculatorPanels or boards for the lower wall.
• Shiplap calculatorBoards and linear feet for a wall.

Decks

• Deck calculatorDecking, joists, beam, posts, railing and balusters.
• Deck framing calculatorJoists, cantilever, beam posts, ledger and hangers.
• Deck joist spanDCA 6 joist spans and overhangs, with snow loads.
• Deck post spacingBeam span between posts and footing size.
• Deck board calculatorWood or composite boards, screws or clips.
• Deck railing height36 in guard rule and openings.