JACK · Roof Calc

Pitch Conversion

Solve for

Rise mm Run mm Pitch °

Pick what you're solving for, then enter the other two. Rise & run can be any matching units (mm, m, anything — they cancel out).

Results

Pitch

—

Rise —

Run —

Pitch —

Slope % —

Slope factor —

Hip / Valley factor —

Slope factor = 1/cos θ — multiply plan dimensions for on-rake (true rafter) lengths. Hip factor = √(2 + tan² θ).

Rafter / Framing

Inputs

Span (wall to wall) mm Pitch ° Eaves overhang (each side) mm

Building length mm

Results

Common rafter (incl. eave)

—

half span × slope factor + eave / cos θ

Half span — wall to ridge centreline —

Ridge height —

On-rake (no eave) —

Eave on-rake —

Hip rafter length —

Ridge length —

Area & Coverage

Inputs

Plan area (footprint) m² Pitch °

Sheet length mm Effective cover mm End lap allowance mm

Results

Roof area (on-rake)

—

plan × slope factor

Sheets required —

Linear m of sheet —

Sheet count assumes single-length sheets where possible. Effective cover refs: Trimdek ≈ 762, Custom Orb ≈ 762, Klip-Lok 700 ≈ 700.

Trim, Battens & Flashings

Inputs

Building length mm Building width (span) mm Pitch ° Eave overhang mm Batten spacing (centres) mm

Results

Gutter / Fascia

Fascia, long sides —

Gable barge (4 rakes) —

Battens

Battens per side —

Total linear metres —

Ridge / Hip

Ridge length —

Hip length (each) —

Total hip linear m —

Valleys are present only on intersecting / L-shape roofs. For those, use the hip factor on the Pitch tab × the plan length of the valley.