What it does
Model one sale across every channel at once and see what each actually pays, with each fee broken down and every rate carrying the page it came from and the date it was last checked.
Currently
Live, browser-only, no signup. Covers eBay (standard, store and Top Rated Plus), TCGplayer (Marketplace, Pro and Direct), Whatnot, Mercari, Misprint and selling in person. Deterministic and rules-based, no LLM and no price lookup, so the same sale always produces the same answer. CSV export is free; PDF is email-gated. It states no tax figure of any kind.
Recently shipped
- Sep 9, 2026Shipped the calculator: six channels, per-fee breakdowns, sourced rate table with staleness flagging, CSV and PDF export.
How it's built
How I built it
This started as a pile of spreadsheets that disagreed with each other. Three different TCGplayer commission figures across two workbooks, an eBay model with no $7,500 tier, and a portfolio tab reporting $8.84 of profit on rows that summed to $1,664.
Checking the rates myself turned up the thing worth building around: almost every error was a fee-base error, not a percentage error. Whatnot charges commission on the item alone and payment processing on the whole order including buyer-paid sales tax. One of the source workbooks added those two percentages together and called it a flat 10.90%, which cannot be right against any base. That is the failure mode this tool is designed to make impossible, because a wrong base still produces a plausible-looking number and nobody catches it.
So the rate table is the product, not the calculator. Every rate carries an effective date, a verified-on date and a link to the platform's own page, and anything not rechecked in 90 days gets flagged in the results instead of quietly served as current. Cardmarket is deliberately missing: its fee table sits behind bot detection, so no row here could carry a verified figure, and an unverified rate is worse than an absent one.
The other decision I would defend hardest is what it refuses to do. It computes no tax. No threshold, no form name, no estimate. The workbook that prompted all this said hobbyists file Schedule D, omitted the collectibles rate entirely, and applied self-employment tax to 100% of net income. Wrong tax guidance published under my name is liability for no product gain, so the tool reports what you were paid and what you spent and hands you a CSV to take to an accountant.
It carries no trading-card imagery, names or data of any kind. An eBay fee is an eBay fee whether the card is Pokemon, Magic or a baseball card, which is exactly why this lives here as its own thing rather than inside a fan project.