You had a good week. Twenty-three sales on Etsy, a handful more through Amazon FBA, and by Friday you're checking your bank deposit expecting it to feel like a win. Instead it's smaller than the number you had in your head - again. Not by a catastrophic amount, just enough to make you wonder if your math is off somewhere. It probably is, and you're far from the only seller getting this wrong.
Most people price their products using a formula that looks like "what I paid" subtracted from "what I sold it for." That number feels like profit, but it almost never is. Between the moment a customer clicks buy and the moment the money actually lands in your account, somewhere between four and seven separate costs quietly take a bite, and most of them never make it onto the notepad or spreadsheet sellers actually use when they're setting a price.
The Real Cost Stack Behind Every Sale
Here's what actually comes out of a typical sale before you see a dollar of profit from it. There's the product itself, obviously, plus packaging - the box or mailer, tape, tissue paper, a thank-you card if you use one - none of which is free even though it feels negligible per unit. Then shipping, which is rarely the flat number sellers assume, because carriers don't just charge by weight; they charge by whichever is bigger, the number on your scale or a size-based "dimensional weight" calculated from the box itself. After that, the marketplace takes its cut - a referral fee if you're on Amazon, a transaction fee if you're on Etsy - followed by a separate payment processing fee that most sellers forget exists because it's deducted automatically before the payout even shows up. Add Amazon's per-unit fulfillment fee if you're running FBA, or Etsy's small listing fee and possible Offsite Ads cut, and a sale that looked comfortably profitable on paper has already lost a meaningful slice before "profit" enters the conversation at all.
None of these costs are hidden exactly - they're all disclosed somewhere in a seller dashboard - but almost nobody adds them up in one place while setting a price, so the gap between expected profit and actual profit becomes a recurring, low-grade surprise instead of a one-time lesson.
The Shipping Trap Almost Nobody Accounts For
Of everything on that list, dimensional weight is the one that catches even experienced sellers off guard, because it's counterintuitive. A seller assumes a light item ships cheap. Carriers don't see it that way. FedEx and UPS price every package by the larger of actual weight or a size-based calculation, with no exception for small or light items. USPS applies the same logic above a certain box size. So a set of ceramic coasters or a stack of stickers in a slightly generous mailer can get billed as though it weighs noticeably more than it actually does, purely because of the space it takes up on a delivery truck. Multiply that extra dollar or two by every order shipped in a month, and it's often the single biggest gap between the shipping cost a seller planned for and the one that actually shows up on the label.
Amazon FBA vs. Etsy - Which One Actually Costs More?
Sellers running both platforms often assume the fee structures are roughly similar. They're not, and the difference matters for how you price. Etsy's fee stack is fairly flat and predictable: a $0.20 listing fee, a 6.5% transaction fee on the item price plus whatever shipping you charge the buyer, and payment processing of about 3% plus $0.25 per order. If a sale comes in through Etsy's Offsite Ads program, that structure changes again, swapping the transaction fee for a larger cut - 12% to 15%, depending on the shop's recent sales volume.
Amazon FBA runs on different logic entirely. Instead of one blended percentage, a seller pays a referral fee that varies by category - as low as 8% for electronics, as high as 45% for certain accessory categories, with most everyday goods sitting around 15% - plus a separate fulfillment fee that Amazon calculates from the product's size tier and weight, similar in spirit to the dimensional weight problem above. A product that just barely lands in Amazon's "Large Standard" size tier instead of "Small Standard" can carry a noticeably higher fulfillment fee for the rest of its life on the platform, regardless of how light it actually is.
Neither platform is universally cheaper. A small, dense, inexpensive item might do better on Etsy; a well-optimized product in a low-referral-fee category might do better on FBA. The only real way to know, for a specific product, is to run the actual numbers rather than trust either platform's marketing page.
A Real Example: What a $24 Candle Actually Nets
Take a soy candle listed on Etsy for $24, with $5.99 charged for shipping, packed in a snug 8x6x4-inch box that weighs 0.9 pounds on the scale. Materials and packaging together run about $7.20 per candle. On paper, that already looks like solid margin: a $24 item costing $7.20 to produce feels like nearly $17 in profit before anything else is considered.
Run the real numbers and the picture changes. That box's dimensional weight comes out to roughly 1.4 pounds against the 0.9 pounds on the scale, which is enough to push it into the next shipping bracket - about $9.75 instead of the $8.25 a seller would expect for something under a pound. Etsy's 6.5% transaction fee on the full $29.99 sale (item plus shipping) comes to $1.95. Payment processing adds another $1.15. The listing fee adds twenty cents. Add up every real cost - materials, packaging, actual shipping, and every fee - against the $29.99 the buyer paid, and the seller nets $9.74. A 32.5% margin, which is respectable, but a good five to seven dollars thinner than the gut-check number most sellers walk around with, and it only holds up because the shipping charge to the buyer was set high enough to begin with.
That gap isn't a one-off mistake. It's what happens by default when pricing is based on the two biggest numbers - cost and price - while every smaller number in between goes unchecked.
Protecting Your Margin Going Forward
A few habits close most of that gap. Weigh and measure the actual shipping box, not just the product, before finalizing a price - dimensional weight is calculated from the carton, and a half-inch of extra padding on each side adds up fast once three dimensions are being multiplied together. Switch to poly mailers instead of boxes for anything that can handle it, since a mailer collapses close to the product's real size and mostly sidesteps the dimensional weight problem entirely. Revisit prices on best sellers every few months instead of setting them once and forgetting them, since carrier and marketplace fees change more often than most sellers check. And before settling on a size tier or category on Amazon, check whether trimming half an inch off the packaging, or reclassifying the listing, would meaningfully lower the fee - sometimes that saves more per unit, permanently, than any amount of ad spend.
See Your Real Number in 30 Seconds
None of this requires a finance degree or a stack of spreadsheets. It requires running the actual dimensions, weight, cost, and price through the same math the carriers and marketplaces use internally, instead of estimating. That's exactly what the calculator on this site does: enter a box size and weight, a product cost, and a selling price, and it returns the real, after-fees profit on that exact listing - for Amazon FBA or Etsy - using current 2026 rate schedules, including the dimensional weight formula every major US carrier actually bills by.
Open the Free Profit Calculator ->
Check it against a best-seller first. For most sellers, it's the first time they've seen the true number attached to a listing they've been running for months - and it's usually the moment pricing stops being a guess.