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Degrees to Roof Pitch Calculator

Convert a measured roof angle in degrees into the rise-over-12 pitch used by US material schedules.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Equivalent pitch

6.93 in per 12 in

High confidence

Rise per 12 = tan(angle) × 12. Round to the nearest common pitch when ordering — material schedules and minimum-slope tables are written against whole ratios.

Surveying an existing roof gives an angle, but almost everything you then need to buy is specified against a ratio: shingle manufacturers publish minimum slopes as 2:12 or 4:12, flashing details assume standard pitches, and material take-off tables are indexed the same way. Converting the measured angle back into rise-per-12 is what lets a survey talk to a supplier. Expect an untidy number — a real roof rarely sits on a whole ratio — and round to the nearest standard pitch for ordering while keeping the measured figure for cutting. Where the rounding crosses a manufacturer's minimum slope threshold, round down rather than up: a covering installed below its stated minimum slope is a warranty problem and, in driving rain, a leak.

Add the equipment this sizes

This result is a specification — 6.928 in per 12 in — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

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 — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • Inverse of the pitch definition: rise per 12 units of run = tan(angle) x 12
  • Manufacturer minimum slopes are commonly stated in rise-per-12, e.g. 2:12 for many asphalt shingle systems with additional underlayment

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Frequently asked questions

My answer is not a whole number. Which way do I round?
Down, if the rounding crosses a manufacturer minimum slope. Covering installed below its stated minimum is a warranty exclusion and a leak risk in driving rain. For cutting, keep the measured figure rather than the rounded one.
Where should I put the inclinometer?
On the rafter or the sheathing, not on the finished covering. Tiles and shingles sit proud of the deck and at a slightly different plane, which biases the reading by a degree or more on some profiles.
Can I measure pitch from inside the loft?
Yes, and it is often easier and safer. Lay the inclinometer along the underside of a rafter. Check two or three rafters — older roofs frequently vary across their length, and an average is more useful than a single reading.