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Roof Pitch to Degrees Calculator

Convert an American rise-over-12 roof pitch into degrees for cutting, setting out and metric drawings.

  • Answers as you type
  • Every formula cited
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Market
Imperial · sales tax
The vertical rise for every 12 inches of horizontal run.

A '6:12 pitch' means 6 inches of rise for each 12 inches of run. Measure the run horizontally, not along the slope — measuring up the rafter gives the rafter length and produces a shallower answer than the true pitch.

Roof angle

26.57 °

High confidence

Angle = arctan(rise ÷ 12), which is exact rather than approximate. Set a mitre saw to the complement of this angle for plumb cuts — a 26.57° roof takes a 63.43° setting on some saw scales.

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Roof pitch expressed as rise per 12 units of run; angle = arctan(rise / 12)
  • Common reference points: 4:12 = 18.43°, 6:12 = 26.57°, 12:12 = 45°

Inputs used

Rise per 12 in of run (in)
6
Final result26.57 °

Confidence note: Angle = arctan(rise ÷ 12), which is exact rather than approximate. Set a mitre saw to the complement of this angle for plumb cuts — a 26.57° roof takes a 63.43° setting on some saw scales.

26.57°1266:12 pitch · 26.57°

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-08-26 · in the site-wide review of 2026-09-06 · v1.0.0

Regulatory standards & verification citations2
  1. Roof pitch expressed as rise per 12 units of run; angle = arctan(rise / 12)
  2. Common reference points: 4:12 = 18.43°, 6:12 = 26.57°, 12:12 = 45°
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

American roofing is specified as a ratio — 4:12, 6:12, 12:12 — while saws, pitch gauges and every metric drawing want degrees, so anyone cutting rafters from a US drawing crosses this boundary constantly. The conversion is an exact arctangent, and a handful of reference points are worth memorising: 4:12 is 18.43°, 6:12 is 26.57°, and 12:12 is exactly 45°. Two practical cautions. First, the run in the ratio is horizontal, so a tape laid along the rafter measures the slope length and yields a flatter figure than the true pitch. Second, saw scales differ: some read the angle from the blade's plumb position rather than from horizontal, so a 26.57° roof may need 63.43° dialled in. Cut one test piece against the actual rafter before committing to a stack of them.

Now that you have the number

These guides cover the work this quantity is for.

Called something else where you work? Roof pitch — the term in each market, how close the equivalence really is, and the standard that governs it.

How to calculate roof pitch to degrees in 2 steps

  1. Rise per 12 in of run (in)The vertical rise for every 12 inches of horizontal run.
  2. Roof angleThe tool computes the roof angle from those figures and shows the formula, its sources, and a confidence rating alongside it.

Roof Pitch to Degrees at common values

Page defaults, not your figures above.

Rise per 12 in of run (in)Roof angle (°)
29.46
314
418.4
522.6
626.6
730.3
833.7
936.9
1039.8
1245

Frequently asked questions

Why does my saw need a different number than this?
Some mitre saw scales read from the blade in its plumb position rather than from horizontal, so they want the complement — 63.43° for a 26.57° roof. Others read directly. Cut one offcut and offer it up to the rafter before running the whole stack.
What angle is a 12:12 roof?
Exactly 45°, because the rise equals the run. It is the one pitch you can check without a calculator, and a useful sanity test that you have entered rise rather than rafter length.
Does the pitch change the material quantity?
Yes. A steeper roof has more surface area over the same footprint, and that is handled by a pitch multiplier rather than by this conversion. Convert the angle here, then apply the multiplier to your plan area before ordering covering.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.