Free calculators
Browser-based tools for checking platform fees, fulfillment drag, and net margin before you make a move.
About SellerGains
SellerGains exists to make platform economics easier to read. The site combines free calculators, practical guides, and a narrower editorial lens so sellers can protect margin without wading through generic advice.
What the site offers
Browser-based tools for checking platform fees, fulfillment drag, and net margin before you make a move.
Guides and reviews that stay close to seller operations rather than drifting into generic ecommerce advice.
The archive expands in deliberate batches so the site can grow without becoming a content landfill.
Editorial stance
Selling online should be profitable, not vague. Every platform structures fees differently, and most sellers end up piecing together numbers from dashboards, blog posts, and spreadsheets that do not agree with each other. SellerGains is built to reduce that friction.
The goal is not to publish everything. The goal is to publish the pages that matter when a seller is evaluating a platform, choosing software, or checking whether a SKU still makes sense after fees.
Have a suggestion or spotted an error? Reach out at [email protected].
Fee verification
Every calculator pulls rates from a single verified fee dataset — not copy pasted into the page. A figure only ships when two independent sources agree, and the verification date under each QuotableFact comes from that same dataset.
When a platform changes its schedule, we refresh the dataset, re-check the math, and surface the new date. Same ledger discipline as the tools: precision first, marketing second.