What does roof pitch mean?

Pitch is how many inches a roof rises for every 12 inches of horizontal run, written like "6:12". The calculator converts your rise and run into pitch, angle, and rafter length.

What is a 6:12 pitch in degrees?

A 6:12 pitch is about 26.6 degrees. A 12:12 pitch (45 degrees) is the steepest common residential pitch.

How do I find rafter length?

The rafter (sloped) length is the hypotenuse of the rise and run. For a 3 ft rise and 4 ft run it's 5 ft. The calculator computes it from your numbers, excluding overhang.

Roof Pitch Calculator

Find a roof's pitch, angle, and rafter length from its rise and run. Enter the two measurements to get the pitch as a ratio (like 6:12), the angle in degrees, and the sloped rafter length.

Roof pitch calculator

Enter rise and run in the same unit (e.g. both inches). Run is the horizontal distance — usually half the span. The rafter length excludes any overhang.

How to use it

Enter the rise (vertical) and run (horizontal) in the same unit.
Run is usually half the building span; the rise is the height from the wall plate to the ridge.
Read off the pitch, angle, and rafter length (which excludes overhang).

How it's calculated

We convert your rise and run into a pitch ratio (rise per 12 of run), an angle using the arctangent of rise ÷ run, and the rafter length as the hypotenuse (√(rise² + run²)). The slope factor is the rafter length divided by the run.

Frequently asked questions

What does roof pitch mean?: Pitch is how many inches a roof rises for every 12 inches of horizontal run, written like "6:12". The calculator converts your rise and run into pitch, angle, and rafter length.
What is a 6:12 pitch in degrees?: A 6:12 pitch is about 26.6 degrees. A 12:12 pitch (45 degrees) is the steepest common residential pitch.
How do I find rafter length?: The rafter (sloped) length is the hypotenuse of the rise and run. For a 3 ft rise and 4 ft run it's 5 ft. The calculator computes it from your numbers, excluding overhang.

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<p style="font:12px sans-serif">Roof pitch calculator by <a href="https://howmanycalc.com/roof-pitch-calculator/">HowManyCalc</a></p>
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Last updated June 2026.