Diagnostic modules
Platform-aware ecommerce margin calculators built on Amazon's published US FBA rate card and referral rules. Active platform: Amazon FBA. Works without Seller Central access.
Amazon FBA is active. Other marketplace modules stay marked as planned until audited.
Choose the margin problem you need to understand. Each diagnostic keeps its source date, methodology, result interpretation, and next step on the calculator page.
Price the real cost of returnsreturn loss · margin drag · recovery bandOpen diagnostic →Find the largest margin leakdiscounts · processors · refunds · chargebacksOpen diagnostic →Spot inbound shipping overpayinbound freight · dimensional weight · rate varianceOpen diagnostic →Check whether a SKU still makes moneyCOGS · Amazon fees · storage residence · contribution marginOpen diagnostic →Set the ad-spend ceiling before losstrue ROAS · profit-safe CPA · break-even ceilingOpen diagnostic →Measure storage and aging pressurecapital · storage · shrinkage · aging · insuranceOpen diagnostic →