Better Roof Calculators. No Strings Attached.
A free roof pitch and slope calculator maintained by an independent developer. No accounts, no paywalls, and results checked against standard rise/run geometry.
What This Site Is
Roof Slope Calculator is a free tool site maintained by an independent developer. Every calculator and guide is available without an account, and the site is currently ad-free.
The calculators use standard rise/run geometry. Calculation logic is covered by automated tests for normal and boundary values, and guides link to original sources such as the IRC and OSHA where safety or code matters.
Results describe roof-plane geometry. They do not replace a site measurement, structural design, local code review, or manufacturer installation instructions.
What Makes Us Different
Runs in Your Browser
All calculations happen locally — nothing is sent to a server. Your measurements stay on your device, and the results are instant.
Interactive Visualization
Most calculators spit out numbers. Ours shows you a real-time SVG roof diagram that changes as you type, so you can see what a 6:12 pitch actually looks like versus a 10:12.
Complete Results
Pitch (X:12), angle in degrees, slope percentage, area multiplier, and slope length for the entered run — all updated as you type.
No Account Required
No sign-ups, no email gates, no "premium" tiers. Every feature is available to everyone, immediately.
How This Site Is Maintained
Independent developer
This site is built and maintained by an independent developer, not a roofing company or manufacturer.
Automated tests
Calculation logic is covered by automated tests, including zero, decimal, and boundary inputs.
Sources and review dates
Safety and code notes link to the original sources and show the date they were last reviewed.
Contact
Corrections, questions, and suggestions are welcome by email — see below.
Our Commitment
RoofSlopeCalculator.org will always be free to use. There are no ads, paywalls, or account requirements.
We're continuously improving our tools — adding new calculators, expanding educational content, and optimizing for every device and screen size. If there's a roofing calculation you need that we don't offer yet, we want to hear about it.
Get in Touch
Have a suggestion, found a bug, or just want to say hello?
contact@roofslopecalculator.org