About RoofCal
RoofCal is a free suite of roof pitch and slope calculators for carpenters, roofers, builders, and homeowners. Every tool runs entirely in your browser — no accounts, no paywalls, no data collection — and every guide is written to be checkable: if we state a number, we tell you where it comes from.
The RoofCal Roofing Editorial Team
Our content is written and reviewed by the RoofCal Roofing Editorial Team — builders and technical writers who translate building codes, manufacturer installation instructions, and framing references into clear, practical guides. We are not a substitute for a licensed contractor or engineer: where a decision is structural, safety-critical, or code-governed, our guides say so and point you to the governing standard.
Editorial standards
- Cited sources. Code minimums cite IBC Chapter 15 and IRC R905; snow-load context references ASCE 7; coastal wind guidance references FEMA coastal construction resources.
- Manufacturer instructions win. Where a product's installation manual is stricter than code, we say so — installing below the manufacturer minimum can void warranties.
- Safety over shortcuts. We don't present pitch alone as a walkability verdict; surface material, moisture, weather, structure, and fall protection all matter, and our guides flag this wherever roof access comes up.
- Dated and maintained. Guide pages show a “last updated” date, and we re-check them against code editions and current manufacturer documentation when we touch them.
How the calculators work
All conversions are pure trigonometry, computed locally in your browser: pitch = (rise ÷ run) × 12, angle = arctan(rise ÷ run), grade = (rise ÷ run) × 100, and rafter length = run × √(1 + (rise/run)²). If you find a result that looks wrong, please tell us — corrections are the fastest way the whole site improves.
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