PriceTag Math is a small collection of free calculators for people who sell online: Etsy shops, small brands and anyone buying ads for the first time. It is made by Muhammad Shujah.
Each calculator shows its formula and a worked example, so you can check the maths yourself. Fee rates come from the platforms' own published policies, linked at the bottom of each page, and are reviewed when the platforms announce changes. The "Last reviewed" date on each page shows when it was last checked.
Spotted a mistake or a fee that changed? Please tell us on the contact page.