Last updated: October 23, 2026. TrowelMath is free because it is supported by advertising and, on some pages, affiliate links. This page explains how that works.
Amazon Associates
TrowelMath is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. As an Amazon Associate I earn from qualifying purchases. Amazon links are marked and open in a new tab; the price you pay is the same.
Advertising
The site may display ads from Google AdSense. Ads are clearly separated from calculator results and are never presented as recommendations.
Our rules
- We only link a product or service where it genuinely helps with the task on the page.
- Affiliate relationships never change a formula, a data point or a result.
- We do not accept payment for reviews, and we do not publish reviews of products we have not evaluated.
- Affiliate links are marked with
rel="sponsored"and a short notice next to the link.
Questions? Contact us.