Premium Lean-To Roof Pitch Calculator

Roof Parameters

Unit System High Precision

Select your preferred measurement system. Calculations maintain 6-decimal precision internally.

Enter at least two values to calculate the roof

Run (horizontal distance) ft

Horizontal distance from wall to ridge

Rise (vertical height) ft

Vertical height from wall top to ridge

Rafter Length ft

Diagonal length of the rafter

Angle (degrees)

Roof slope angle (0° = flat, 90° = vertical)

Building Width ft

Length of the building parallel to the ridge

Rafter Spacing

Distance between rafters. Metric option available when using metric units.

Note: 60 cm ≈ 23.62 inches

Overhang Length ft

Extension of rafter beyond building wall

Roofing Material

Material type for accurate quantity estimates

All calculations maintain 6-decimal precision with exact fraction matching

Enter at least two roof parameters and click "Calculate" to see results

Example: 4:12 Pitch

Run: 12, Rise: 4

Example: 30° Angle

Run: 10, Angle: 30