Pitchwright Framing Calculator

What it does

For carpenters framing roofs and stairs on the job: Pitchwright works like a handheld, offline, and you pay once. Rafters, hips and stair stringers come out right first time, in feet-inch or metric, without an $80+ handheld or a yearly subscription.

Worked examples

• Common rafter. 6:12 pitch, 12 ft run -> common rafter 13-5 (then less ridge).
• Stair layout. 10'-1" rise, 15'-5" run -> 16 risers of 7 9/16, 15 treads.
• Hip valley. 6:12 pitch, 12 ft run -> hip or valley 18-0.
• Jack rafters. Jacks at 16 in OC on 6:12 -> common difference 17 7/8.
• Crown miter. Crown, 38 degree spring on a 90 degree corner -> miter 31.62.
• Metric rafter. Metric: 30 degree pitch, 4 m run -> rafter 4619 mm.

How it's calculated

Every trade key and the formula behind it, as shown in the app's key guide. A second legend is the shifted function.

Pitch °Pitch / Cut angles

Stores the typed pitch as x in 12, or solves pitch = rise ÷ run; shifted gives the plumb cut atan(pitch ÷ 12) and level cut 90° − plumb.

Rise Hip/VRise / Hip or valley

Stores the typed rise, or solves it from two of run, diagonal and pitch; shifted gives the regular hip or valley = run × √(2 + (pitch ÷ 12)²).

Run JackRun / Jack rafters

Stores the typed run, or solves it from two of rise, diagonal and pitch; shifted steps through jack rafters, each shorter by spacing × √(1 + (pitch ÷ 12)²).

Diag TailDiagonal / Rafter tail

Diagonal or common rafter = run × √(1 + (pitch ÷ 12)²), then less half the ridge; shifted stores the typed overhang or gives the tail = overhang × the same factor.

Stair TreadStairs / Tread and code

Lays out a stair for the stored rise: risers = rise ÷ desired riser, rounded and kept within the code; a typed length sets the desired riser. Shifted sets the tread or switches code.

BdFt CrownBoard feet / Crown moulding

Board feet = thickness × width × length ÷ 144 cubic inches, or cubic metres under metric; shifted gives crown mitre and bevel for the typed or stored corner.

OC StudsOn-centre spacing / Stud count

Stores the typed spacing, or steps through 16, 24 and 12 inches (400, 600, 300 mm); shifted gives studs = ⌈wall ÷ spacing⌉ + 1 for the typed wall length.

Area SheetsArea / Sheets and blocks

Stores the typed area; shifted gives whole sheets = ⌈area ÷ sheet⌉, roofing squares = area ÷ 100 square feet and blocks.

Conc BagsConcrete volume / Concrete bags

Stores the typed volume, or area × a typed thickness, in cubic yards or metres; shifted gives bags = volume ÷ bag yield plus the typed waste percent.

Circle ArcCircle / Arc

A typed length sets the radius, a plain number the polygon sides; then side = 2R × sin(180° ÷ n), diameter, circumference and area. Shifted solves an arc from a chord or angle.

Results are computed from the formulas shown for each function and are provided for reference only. Verify all dimensions before cutting or building, and confirm stair and structural requirements against the code in force and the authority having jurisdiction. The developer accepts no liability for loss or damage arising from use.