About MarginGlass
True margin, minus the fine print.
MarginGlass started with a spreadsheet Eric built for his own marketplace store, trying to figure out why the same $40 sale sometimes cleared $19 and sometimes cleared $11 — the platform's own settlement reports never broke it down the same way twice. The calculators he found online were either built around the wrong fee schedule, out of date, or just returned a number with no way to check the math behind it.
So he built something better. MarginGlass is a collection of free, no-account- required calculators that show sellers their real margin after Amazon, Etsy, Shopify, Stripe/PayPal, or eBay fees — every line item shown, cited to that platform's own published fee schedule.
Eric has run online storefronts across a few marketplaces and spent more hours than he'd like to admit reconciling settlement reports against what a sale price should have paid out. MarginGlass exists so that reconciliation takes ten seconds instead of a spreadsheet.
Part of the Veraino network of free tool sites.
How it works
Every tool on MarginGlass is grounded in a documented, citable method — a published formula, an authoritative standard, or a well-established model. We don't approximate or invent numbers. If we can't cite a primary source for the logic, we don't publish the tool.
For MarginGlass specifically, that means every calculator is built directly from a platform's own published fee schedule — referral fee tables, fulfillment fee tiers, payment processing rates — re-checked against the live schedule at least once a year, with the review date shown on the tool itself.
Our commitments
- Free, no sign-up required. Every tool on this site is free to use with no account, subscription, or paywall.
- We show our work. Every tool explains its methodology, cites its sources, and surfaces assumptions — so you can verify the logic, not just trust the output.
- Honest about limitations. Where precision is limited or assumptions are required, we say so. Tools compute; they don't replace professional judgment.
- Kept current. Tools that use figures that can change over time carry a “last reviewed” date and are treated as an ongoing maintenance responsibility, not a one-time build.
Get in touch
Questions, corrections, or suggestions: contact@marginglass.com. Eric reads every message personally.