I built this after the worst-best year of my selling career.
NetSellerProfit is a one-person project run by Marcus Feld. It exists because I spent a decade optimizing for the wrong number, and I do not want you to lose the years I lost finding the right one.
I have been selling physical products online since 2014. I started on eBay and Amazon, added a Shopify store in 2017, opened an Etsy shop for a handmade line in 2019, and jumped onto TikTok Shop the month it opened to US sellers. Across those channels I have shipped everything from kitchen tools to craft supplies to a private-label line I still run today. I am not a consultant who read about this — I have paid every one of these fees out of my own bank account.
The year that changed how I think was my biggest revenue year. I crossed roughly $4M in gross sales across four channels and felt unstoppable — right up until I did a real profit-and-loss and found that after landed COGS, referral and payment fees, fulfillment, returns, and ad spend, I had kept almost nothing. Some SKUs I had scaled aggressively were losing money on every unit. My dashboards were celebrating the exact products that were quietly bleeding me.
The problem was not that I was bad at math. The problem was that my numbers lived in four different spreadsheets, each with slightly different fee assumptions, none of them recalculating in real time, and none of them showing me the only figure that mattered: net profit per unit, after everything, on each channel. So when I raised a bid or dropped a price, I was flying blind.
What NetSellerProfit actually is
I built the tool I wish I had had. You drop in one SKU — sale price, landed cost, ad spend, shipping — and it applies each platform's current 2026 fee schedule and shows your true net profit and margin across TikTok Shop, Amazon FBA, Etsy, and Shopify, side by side, before you commit to a price. No login. No account. No data harvesting. It runs entirely in your browser.
The Knowledge Center is where I write up what I have learned the expensive way — how each fee is really structured, where the cliff edges are, and the specific levers I use in my own stores to claw margin back. Every article is written from the operator's seat, not paraphrased from a help page.
What I am not
I am a seller, not a CPA, tax attorney, or licensed financial adviser. The calculator is a high-precision estimator and the articles are field notes, not professional advice. Platform fees change, and category-specific rates and dimensional weight can move your real numbers — always cross-check against your own payout statements, and for tax, legal, or accounting decisions, hire a licensed professional. Where I write about sales tax or nexus, treat it as a starting map, not a ruling.
NetSellerProfit is free to use, and I keep the lights on through display ads and a small number of affiliate links to tools I actually use (clearly marked on the Seller Tools page). If a link ever costs you more or steers you wrong, email me and I will pull it.
How I think
The three principles every article and feature is measured against.
Net first, always
Every screen and every article leads with the number that pays you. Revenue and GMV are context, not the score. I surface what actually hits the bank.
Written from the seat
If I have not actually run into a problem in my own stores, I do not pretend to have the answer. Field notes over paraphrased help-center copy.
Honest about fees
Platform takes change quarterly. I surface defaults, expose every override, date my fee schedules, and tell you when a number is going stale.
Questions, corrections, or a fee I got wrong? I read every message: Get in touch →
Run your first SKU.
Drop in a single product and see what it actually earns on every channel — in the next 30 seconds.