Methodology

Where the rates come from

Every rate is taken from the marketplace’s own published fee page and stored in one data file with the date it was last checked and the page it came from. The table below lists each marketplace with its sources and how reliable the source is.

Reliability levels

• Official: the figure is read from the marketplace’s own fee page.
• Media: the figure comes from a news or industry publication because the marketplace does not publish it in an easily readable form. Such pages say so, and you should confirm the figure in your seller account.
• Entered by you: figures that depend on your product or contract, such as Amazon FBA fulfilment fees or the commission rate on Prom.ua and Rozetka, are never guessed. The calculator asks you to enter them.

How the formulas work

Each calculation is a small function with no dependence on the page, and each is covered by automated tests that check known cases, edge cases such as zero and negative inputs, and, for the pricing calculators, that the price returned really reaches the target and that one cent less does not.

Amounts are rounded to cents at each fee, the way a statement would show them. Where a marketplace’s rate steps at a price threshold, the pricing calculators search for the lowest price that genuinely meets your target rather than relying on a closed formula that could miss a jump.

Everything runs in your browser. The prices and costs you type are not sent to any server.

What the calculators do not include

• Income tax, sales tax and VAT you owe on your own sales. The Ukrainian pages link to a separate FOP calculator for sole proprietor taxes.
• VAT charged by a marketplace on its own fees, regulatory or deposit fees in some countries, and account-level charges such as long-term storage.
• Discounts tied to seller status, subscription tiers and promotions.
• Currency effects other than the conversion fees that the marketplace itself publishes.

Keeping rates current

Marketplaces change fees without notice. Each calculator shows the date its rates were last checked, and the date is updated whenever the numbers are rechecked. If a figure on a calculator differs from the marketplace’s own page, the marketplace’s page is correct.