/// Answer-first planning notes
What pitch, angle, and rafter multiplier match my rise and run?
| Planning input | Calculation role | Check before ordering |
|---|---|---|
| Rise | Forms the slope ratio | Measure under the same convention as run |
| Run | Normalizes pitch and angle | Do not substitute total span |
| Horizontal span | Scales the rafter-line result | Add overhang and ridge details separately |
Length conversions for the displayed roof geometry use the international foot, exactly 0.3048 meter.
Evidence: National Institute of Standards and Technology/// Formula & field notes
How this roof pitch estimate works
FormulaSlope = rise ÷ run. Pitch = slope × 12. Angle = arctan(slope). Rafter multiplier = √(1 + slope²).
Worked example
A 6 in rise over 12 in run is a 6:12 pitch, 50% slope, and about 26.57°.
/// Source trail
Data & assumptions
Every source has a declared scope. A reference can support a conversion or product assumption without turning this estimate into a supplier quote.
Exact international-foot to meter conversion; U.S. survey-foot conversion is explicitly outside this claim.
Effective 2025-08-18 · Reviewed 2026-07-15 · Next review 2027-07-15Independent confirmation that one international foot equals exactly 0.3048 meters; U.S. survey-foot conversion remains distinct.
Effective 2025-06-10 · Reviewed 2026-07-15 · Next review 2027-07-15/// Common questions
Roof Pitch calculator FAQ
What does a 6:12 roof pitch mean?
The roof rises 6 units for every 12 horizontal units. The ratio is independent of whether the units are inches, centimeters, or another consistent measure.
Is roof pitch the same as roof angle?
They describe the same slope differently. Pitch is commonly expressed as rise per 12 in the U.S.; angle is measured in degrees.
Does rafter length include the overhang?
No. The calculated length uses the horizontal span you enter. Add the actual horizontal overhang and other framing details separately.