What this assumes
- A percentage fee is a percentage of the advertised total, meaning the price times the count. It is not charged on top of the other fees. Some sellers do compound them, and those sellers are worse than this tool will tell you.
- Tax applies to the advertised total plus the fees counted in that line. The mandatory-only figure and the everything figure are therefore taxed on different bases, which is why they are given separately.
- Each fee is rounded to the cent on its own line, the way a real bill does it, and the lines are then added as whole cents. Twenty fees give exactly the same answer as one.
- The markup figure counts fees only. Tax is left out of it, because the seller does not keep it.
- The mandatory-only total is the number worth comparing between two sellers. An optional extra is yours to refuse, so it says nothing about what the seller is charging.
Where the law stands
The FTC's Rule on Unfair or Deceptive Fees took effect on 12 May 2025. It requires the total price, including all mandatory fees, to be shown up front, and it bans burying them later in checkout. The scope is narrower than people assume: it covers live-event ticketing and short-term lodging, and not every industry. A late fee on a broadband bill or a car rental is not reached by it. Elsewhere in the United States drip pricing is still handled case by case under Section 5 of the FTC Act.
This describes published regulation. It is not legal advice, and rules in this area have changed more than once. The field guide entry carries the primary sources.