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Affiliate disclosure

How this free site is paid for, in plain terms.

Updated October 15, 2026.

Amazon Associates

As an Amazon Associate we earn from qualifying purchases. Under most calculator results there is a short list of tools and supplies for that job. Each link opens an Amazon search for a type of item, not a product we chose for its commission. Links are marked rel="sponsored", carry no product images, prices or ratings, and do not appear in guides or embedded calculators.

Our own products

We sell a Renovation Planner workbook and a DIY Materials Handbook on Gumroad. They are mentioned in one line after a calculator result and at the end of guides. The calculators stay free and work the same whether or not you buy anything.

Advertising

The site may show ads served by Google AdSense. Ads are labelled by Google and are never styled to look like calculator results or site links. How ad cookies work and how to opt out is in the privacy policy.

What never changes

No payment changes a formula, a default or a result. If you think a page reads like an ad, tell us.