CalcRoofPitch.com is a free resource built for homeowners, contractors, and DIYers who need fast, accurate roof pitch calculations without the guesswork.
Why We Built This Site
Roof pitch calculations seem simple until you’re actually on a job. You’ve got a speed square in one hand, a tape measure in the other, and you need to know: Is this a 4:12 or a 5:12? What angle is that? How much extra roofing material do I need for this slope?
Most online calculators make you convert units yourself, don’t explain the formula, and bury the result in ads. We built CalcRoofPitch.com to fix that — clean, fast tools that show their work so you actually understand the answer.
What We Cover
Our calculator suite covers every roof pitch calculation a contractor or homeowner runs into:
- Basic pitch calculator — rise over run, expressed as X:12
- Pitch to degrees — convert any slope to an angle for your saw settings
- Rafter length — calculate actual rafter length for any span and pitch
- Roof area multiplier — how much extra roofing material a slope requires
- Speed square readings — decode the Common and Hip/Valley columns
- Metric support — work in millimetres, centimetres, or metres
Every tool shows the formula it uses and explains each variable in plain English — because understanding the math means you can double-check the result yourself.
Our Standards
All calculations on this site follow the formulas established in the International Building Code (IBC) and International Residential Code (IRC), and align with guidance from the National Roofing Contractors Association (NRCA). Where fall protection thresholds are relevant (slopes over 4:12), we reference current OSHA 29 CFR 1926.502 standards.
Our pitch classification categories — flat, low-slope, conventional, and steep — match the definitions used across the professional roofing industry.
How Our Calculators Work
Every calculation runs entirely in your browser using JavaScript. We don’t collect, store, or transmit your measurement inputs. No account required. No signup. Just enter your numbers and get your answer.
Questions or Corrections?
If you spot an error, have a suggestion, or want to request a specific calculator, we want to hear from you. Use our Contact page to reach us directly.
We review every message and take accuracy seriously. If something doesn’t look right, tell us — we’ll check it against the source code and correct it if needed.