About Our Calculators

Methodology

Our calculators use the published fee structures from each platform's official documentation. We compute listing fees, transaction fees, payment processing charges, and any additional platform-specific costs based on your inputs. Each fee in the result panel links directly to the source we used and shows the date it was last verified.

Fee Sources & Verification

Every fee in our calculators is traceable. The table below lists every fee we apply, the official source we consulted, and when we last verified the rate. If you spot a rate that has changed, please let us know.

Etsy

Last verified: 2026-05-03

Shopify

Last verified: 2026-05-01

Dropshipping

Last verified: 2026-05-01

Amazon FBA

Last verified: 2026-04-28

Frequently Asked Questions

How accurate are these calculators?+
Each fee comes from the platform's official documentation, and the result panel on every calculator links back to that source with the date we last verified the rate. The math is pure functions covered by unit tests. Real-world accuracy depends on edge cases we don't model — region-specific surcharges, promotional discounts, account-tier differences. Use our numbers as a strong baseline, then verify your own account against your platform's fee schedule before pricing decisions.
How often do you update the fee data?+
We re-verify every fee quarterly against the official platform source. We also push immediate updates when readers flag a discrepancy or when a platform announces a fee change. Every fee entry has a "last verified" date you can see in the result panel and on the /about/ fee-sources table.
Is CommerceProfitLab free? How do you make money?+
All calculators and guides are 100% free with no signup, no email gate, and no upsell. We don't sell user data and we don't require accounts. Eventually we may add unobtrusive sponsorships from ecommerce tools we genuinely vouch for, but the calculator results themselves will never be paywalled or affiliate-influenced.
Why don't you have an account system?+
Because the tool doesn't need one. Your inputs save to your browser's localStorage so you can come back and find the last numbers you ran. We don't want to be in the business of storing your business data on our servers, and you shouldn't have to trust us to keep it secure. If you want to share or archive results, every calculator has an "Export CSV" button.
Can I use these calculators for my client work or as part of my service?+
Yes — the tools are free to use for any purpose, including commercial. If you're building a course, consulting practice, or freelance bookkeeping service for ecommerce sellers, feel free to link to specific calculators or embed screenshots in your work. We just ask that you don't scrape and rehost the calculators as your own.

Disclaimer

This tool provides estimates only and does not constitute financial advice. Actual fees may vary based on your location, account type, currency conversion rates, and promotional programs. Always verify with your platform's official fee schedule before making business decisions.

Last updated: May 2026

How we keep these numbers honest

Our calculators are only as trustworthy as the data behind them. Every fee in every result links to its source — and here's the process behind that.

  1. Step 1

    Pull from the source

    Each fee starts from the platform's official pricing or fee page — never a blog post, never a screenshot.

  2. Step 2

    Encode the formula

    The rate goes into platforms.json with a verified date. Calculations are pure functions, unit-tested.

  3. Step 3

    Link the proof

    Every fee row exposes the source URL and the date we last verified it — so you can audit the number yourself.

  4. Step 4

    Re-verify on cadence

    We re-check rates each quarter, and immediately if a reader flags a discrepancy. Verified dates always reflect the most recent check.