Hi Product Hunt 👋

I've been a developer for 8 years, and Fee Math is the first site I've built for myself. There was always a client project or a deadline in the way, so this one kept getting pushed back. This year I finally made the time.

Full honesty: I'm not a designer. About 90% of the design was done with AI, and I focused on what I'm good at: the calculations, the data and making it fast. If something looks off, I'd really like to hear it.

Why fee calculators? Every marketplace hides its real cut in a different place. Etsy splits it into transaction, processing and listing fees. eBay charges its fee on shipping and sales tax too. Amazon FBA adds fulfilment, storage and placement fees on top of the referral fee. It's easy to price an item and only later find out you kept a lot less than you thought.

Fee Math is a set of free calculators that show every fee on one order and your real profit and margin before you set a price:

• Etsy: fees, profit, free-shipping price, Offsite Ads, target price

• Amazon FBA: profit & ROI, referral fee, price, FBA vs FBM

• eBay: final value fee by category, monthly profit

• TikTok Shop, Depop, Poshmark, Mercari, Whatnot

• PayPal, Stripe, Square, Shopify Payments

A few things I cared about:

– Rates come from each platform's official fee pages, with the update date and source shown on every calculator

– No sign-up, everything is calculated in your browser

– Plain-English guides next to the tools (e.g. eBay fees 2026, FBA vs FBM)

I'd love feedback on three things: which marketplace or fee I should add next, whether any number looks off for your real orders, and anything in the design that gets in your way. I'll be here all day answering questions.