Every other tool needs your sales data — past transactions, settlements, API connections. If you're not selling yet, you can't use them. FineMargins only needs your product. Price, weight, dimensions, category. Five minutes of input. Every fee computed from published rate cards across every platform you're considering.
The cost structure before you commit — not after you've invested in inventory, branding, and a seller account.
You enter your product.
Price, weight, dimensions, category, how you'd fulfil it. Five minutes. Then we compute:
Every published fee applied to your product — referral, fulfilment, storage, surcharges, subscription allocation. Not "about 15%." The exact number for your category, your weight band, your size tier, your price point. Every source linked.
Which fees have alternatives. Which programmes you'd qualify for. What configuration choices exist and what each one costs. On Amazon alone, 1,652 things you can change — most sellers don't discover them until months into selling.
At what volume does a Professional plan become cheaper than per-item fees? At what fulfilment cost does FBA become cheaper than FBM? At what price point does your product cross a referral fee band? The thresholds — before you price your product.
The same product across Amazon, eBay, Walmart, and Shopify. Not a fee table — a structural comparison of what each platform charges, what it includes, and what you'd need to provide. With the seller-provided costs you'd need to fill on Shopify to make the comparison real.
| Referral fee (15%) | $3.75 |
| FBA fulfilment | $3.95 |
| Fuel surcharge (3.5%) | $0.14 |
| Platform fees | $7.84 |
| Payment processing (2.9% + $0.30) | $1.03 |
| Platform fees | $1.03 |
Illustrative Pre-Entry Check output. In the platform, every line is computed for your product across the platforms you select.
Amazon charges 15% referral in this category — $3.75 on a $25 product. But the referral fee is one of several fee lines on a typical FBA product. FBA fulfilment and the 3.5% fuel surcharge add another $4.09, bringing platform fees to $7.84 — 31.4% of the sale price. A seller who budgeted for 15% is paying more than double.
On a $18.99 product, Shopify's platform fee is $0.85 per sale — Amazon charges $7.20 for the same product. But Shopify includes nothing else. The seller provides fulfilment (Amazon's FBA runs $4.35/unit on this product), buys every visitor (Shopify has no marketplace traffic — 15% of revenue on advertising is a realistic starting point), and handles returns. Add those back and the "cheaper" platform can cost more once you account for everything the seller provides separately. FineMargins shows exactly where the crossover happens.
By then you've committed inventory, opened a seller account, invested in listings and branding. If the unit economics don't work, you find out after the investment — not before. The Pre-Entry Check costs $9.99 and takes five minutes. The inventory commitment costs thousands.
Enter your product details — price, weight, dimensions, category, fulfilment preference.
Select which platforms you're considering — Amazon, eBay, Walmart, Shopify, any combination.
Every fee on each platform computed from published rate cards. Every number sourced. Every source linked.
What you get: The full cost breakdown for your product on every platform you selected. Which fees apply. Which programmes you'd qualify for. Which costs have cheaper alternatives. Where the price and volume thresholds sit. The information you'd spend weeks assembling from platform documentation — in five minutes.
What happens next: If you start selling and want ongoing analysis — monthly re-computation, settlement reconciliation, what-if simulation, multi-product portfolio analysis — the subscription plans start at $29/month. The Pre-Entry Check credit applies to your first month.
FineMargins launches September 2026. The Pre-Entry Check is the first feature available. Sign up to be first in line.
See what the analysis looks like on a real product →
Amazon fees → · eBay fees → · Walmart fees → · Shopify fees →
Amazon vs eBay → · Amazon vs Walmart → · Amazon vs Shopify →
Every fee in the Pre-Entry Check is computed from published platform rate cards. 8,938 fee records across 26 marketplaces. Every source linked. No estimates. How we get our numbers →