Calculation Methodology

Fee source tracking

Marketplace fee rates can change. Fee schedules are designed to be verified against official marketplace documentation before rates are added to calculators.

Effective dates

Fee records can include effective-from and effective-to dates so future calculators can select the rate schedule that applies to a chosen date.

Last verified dates

Relevant calculator pages will display the last verified date and official source information from centralized configuration, rather than manually typed page copy.

Estimate boundaries

Calculations are estimates for planning. Sellers should confirm current fees and account-specific details with each marketplace before making financial decisions.

Money precision

Money calculations use integer cents in the calculation engines where practical, with percentage rates represented as basis points. This helps avoid floating-point drift in fee and profit results.

Marketplace-specific fee bases

Fee bases differ by marketplace. For example, one marketplace may apply a fee to buyer-paid shipping, while another may include tax in a processing or final-value-fee base. SellerFormulas keeps those assumptions with the relevant calculator engine and source notice.

Official settlement differences

Marketplace settlements can include account-specific adjustments, refunds, optional services, shipping labels, inventory charges, taxes, promotions, or seller-program rules that a calculator does not automatically know. Use seller portals and official statements for critical decisions.