About this site
A set of free material calculators built around one idea: tell you what to buy, not just the raw math — and get the numbers right.
Accuracy first
Every formula and constant — bag yields, coverage rates, pitch factors — is checked against manufacturer spec sheets and industry standards, and runs through an automated accuracy test on every update.
Built to be useful
Each tool leads with a purchase decision (bags, gallons, bundles), gives a copy-ready shopping list, and saves your inputs in the page link so you can share or revisit a project.
No sign-up, no clutter
The calculators are free and run entirely in your browser. Nothing to install, no account, no data collected to use them.
Always improving
More calculators and features (multi-section areas, cost estimates, metric units) are on the way. Tell us what you’d find useful.
These tools give estimates to help you plan and shop. For structural or load-bearing work, follow local building codes and consult a qualified professional — a calculator is not an engineer.