# How to Measure Roof Pitch Measure rise over 12 in of run from the attic or roof, read an angle, or work it out from plans, then convert. Guide page: (published 2026-10-05, updated 2026-10-05). This Markdown version has the guide's key points, outline, FAQs and sources; the full article, with its worked examples and diagrams, is on the page. ## Key takeaways - Pitch is the rise in inches for every 12 inches of horizontal run, written like 6/12. - The safest measurement is usually from the attic, on the underside of a rafter, with a level and a tape. - Any angle reading converts to pitch with pitch = 12 × tan(angle). - On plans, the run of a symmetrical gable is half the span, so pitch = rise ÷ (span ÷ 2) × 12. - Falls are the leading cause of death in construction, according to OSHA. Don't climb onto a roof without proper fall protection. ## In this guide 1. [What you are measuring](https://www.howmanyyardsdoineed.com/guides/how-to-measure-roof-pitch/#what-you-are-measuring) 2. [Method 1: from the attic](https://www.howmanyyardsdoineed.com/guides/how-to-measure-roof-pitch/#from-the-attic) 3. [Method 2: on the roof surface](https://www.howmanyyardsdoineed.com/guides/how-to-measure-roof-pitch/#on-the-roof) 4. [Method 3: angle finder or phone](https://www.howmanyyardsdoineed.com/guides/how-to-measure-roof-pitch/#angle-finder) 5. [Method 4: at the gable end](https://www.howmanyyardsdoineed.com/guides/how-to-measure-roof-pitch/#at-the-gable) 6. [Method 5: from plans or dimensions](https://www.howmanyyardsdoineed.com/guides/how-to-measure-roof-pitch/#from-plans) 7. [Convert and check your reading](https://www.howmanyyardsdoineed.com/guides/how-to-measure-roof-pitch/#convert-and-check) 8. [Ladder and roof safety](https://www.howmanyyardsdoineed.com/guides/how-to-measure-roof-pitch/#ladder-and-roof-safety) ## Frequently asked questions ### Can I measure roof pitch without going on the roof? Usually, yes. Measure the underside of a rafter from the attic, read the pitch at a gable end from a properly set ladder, or work it out from the plans or from the rise and span. All of these give the same rise-over-run ratio as measuring on the roof. ### What if my level is shorter than 12 inches? Measure the rise over whatever horizontal length your level gives you, then scale it. For example, a 2 1/2 inch rise over 6 inches of run is 5 inches over 12, a 5/12 pitch. The ratio is what matters, not the length of the level. ### Do both sides of a gable roof have the same pitch? Not always. Many gable roofs are symmetrical, but some are not, and additions or dormers often have their own pitch. Measure each roof plane you are estimating. ### How do I turn an angle in degrees into a roof pitch? Multiply 12 by the tangent of the angle. A 30 degree reading is 12 × tan(30°) = 6.93, about a 7/12 pitch. The roof pitch calculator does the conversion the other way as well. ### How accurate does a pitch measurement need to be? For estimating materials, small errors have a small effect: the slope factor for 6/12 is 1.118 and for 6.5/12 it is 1.137, under 2 percent apart. For framing or product limits, measure carefully and confirm against plans. ## Related calculators and guides ### Calculators - [Roof Pitch Calculator](https://www.howmanyyardsdoineed.com/roof-pitch-calculator/) — Pitch as x/12, roof angle in degrees, slope percentage, and the sloped length for a given horizontal run. - [Roofing Calculator](https://www.howmanyyardsdoineed.com/roofing-calculator/) — Roof area, roofing squares, and shingle bundles from a footprint and pitch, using the coverage on your shingle wrapper. ### Guides - [Roof Underlayment Basics: Synthetic, Felt, and Ice Barrier](https://www.howmanyyardsdoineed.com/guides/roof-underlayment-basics/) — Underlayment and ice barrier explained, with laps, low-slope rules, and a worked roll count for a gable roof. - [How to Measure an Irregular Area](https://www.howmanyyardsdoineed.com/guides/measuring-irregular-areas/) — Split odd shapes into rectangles, triangles, circles, and trapezoids, then average width and depth. ## Sources - [Fall Prevention Campaign](https://www.osha.gov/stop-falls) — Occupational Safety and Health Administration. Checked 2026-10-05. - [29 CFR 1926.1053: Ladders (construction)](https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.1053) — Occupational Safety and Health Administration. Used for: Side rails extend at least 3 ft above the upper landing; base set out about one-quarter of the working length; face the ladder; at least one hand on the ladder. Checked 2026-10-05. - [NIST Guide to the SI, Appendix B.9: Factors for units listed by kind of quantity](https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b9) — National Institute of Standards and Technology. Used for: 1 ft = 0.3048 m (exact); 1 in = 2.54 cm (exact). Checked 2026-10-03. **Estimate only.** Results are planning estimates computed from the numbers you enter. They are not engineering, structural, or code advice. Confirm quantities, product yields, and installation requirements with your supplier, the product label, and your local building authority before you order or build.