Built for practical planning
About Project Buy List
We build focused tools that turn room measurements and product details into purchase-ready material estimates.
Why this site exists
Home projects often start with a simple question: how much material should I buy? The arithmetic may be straightforward, but openings, waste, product coverage, package sizes, and unit conversions make the final purchase less obvious.
Project Buy List keeps those steps together and explains them in plain English.
What we value
Show the formula, intermediate values, assumptions, and limits.
Translate calculated need into full containers, pieces, sheets, rolls, or boxes.
Publish a calculator after its specification and contract tests are ready.
Use estimates to prepare, then verify local products and site conditions.
How the collection grows
Calculators are organized by project area so related tools form a useful planning path. New categories become public only when they contain a tested calculator.
Read our methodologyHow we maintain the tools
Each published calculator has a written specification, a framework-independent calculation module, reference examples, and contract tests for validation, unit conversion, and package boundaries. When a formula or assumption changes, the related explanation and example are reviewed together so the page remains consistent with the result.
If you find an edge case, use the Contact page to report the calculator, units, inputs, result, and expected behavior without sharing private property details.