About RoofCalcWorks
RoofCalcWorks is a free roofing calculation and estimation platform for homeowners, DIY users and contractors. Our goal is simple: help you measure, quantify and budget a roofing project with transparent formulas — no sign-up, no hidden agenda.
What we solve
Roofing projects start with questions: What is my actual roof area? How many shingles do I need? What should a replacement realistically cost? Our calculators answer these questions step by step, and every result can feed directly into the next calculation.
How our calculators are built
Every calculator on this site runs on one shared calculation engine. The formulas, assumptions, rounding rules and limitations are documented openly on our Methodology page. Content is maintained by the RoofCalcWorks Editorial Team and reviewed regularly.
Data & formula sources
Formulas and conventions follow recognised technical references: the International Residential Code (IRC), Chapter 9 — Roof Assemblies for minimum roof slope and covering requirements, and NRCA steep-slope roofing guidance for roof geometry and roofing-square conventions. Product values — bundles per square, accessory coverage, fastener schedules — come from manufacturer installation instructions and product data sheets (asphalt shingles are specified by ASTM D3462). Cost ranges come from published national roofing cost data (Angi 2026, cross-checked against Fixr), and every price value carries a source, region, update date and version. Full detail is on the Methodology page.
How we keep content up to date
The price dataset is reviewed quarterly and versioned — the current dataset is p1-data-1 (September 2026), and the calculation engine carries its own version (p1-v1). Each calculator page lists its Sources and last-updated date, so you can always see what a result is based on and when it was last checked. If something looks out of date or wrong, tell us via the contact page and we will correct it.
Contact
Questions, corrections or feedback? Reach us via the contact page.