FBA Shipping Calculator: The Full Breakdown, With a Worked Example

Two tools, one search term

Search this phrase and you land on two different products wearing the same name. Yotpo's calculator, for example, is built to answer "what will Amazon actually charge me and what's left over?" — you enter price, cost, category and dimensions, and it walks referral fee, fulfillment fee and storage fee down to a net profit per unit. Freightos's calculator answers a different question entirely: "what does it cost to physically move this shipment from my supplier to an Amazon fulfillment center?" It pulls live rates from freight forwarders for ocean, air and trucking, and it's genuinely useful for that job — it's built on real carrier data, not a static fee table.

Neither tool replaces the other, and neither is wrong to call itself an FBA shipping calculator. If you're pricing a listing before launch, you want the fee calculator. If you're deciding whether to ship a container by sea or split it across air freight, you want the freight calculator. Using the wrong one gets you a number that's accurate for a question you weren't asking.

Worked example: one SKU, real math

Say you're selling a Home & Kitchen product at $24.99, costing $6.00 to make and $1.20 to ship to Amazon per unit. The packaged box is 10" x 8" x 3" — 0.139 cubic feet.

• Referral fee: Home & Kitchen is charged at 15% of selling price — $3.75 per unit.
• Monthly storage: charged per cubic foot of space occupied, at one rate for January–September and a materially higher one for October–December — historically around three times the off-peak rate on standard size. Amazon publishes the current per-cubic-foot rate by size tier inside Seller Central and revises it, so read yours off the Fee Preview report rather than any figure quoted elsewhere, including here. Whatever the rate, this SKU occupies 0.139 cubic feet, so the monthly charge is that rate × 0.139 per unit.
• Fulfillment fee: set by size tier, which is decided by the greater of actual weight or dimensional weight. Pull the dollar figure for your tier straight from Amazon's current fee table — that number moves on Amazon's schedule, not the calculator's, so don't let a tool cache it.

Add those against your selling price and you get net profit per unit. The line that actually swings month to month — and the one most sellers forget to re-run — is storage. The exact same SKU, same warehouse, typically costs several times as much to store in Q4 as it does in Q2.

What each fee is actually based on

Every FBA fee calculator is running the same underlying arithmetic. The table below is the arithmetic, stripped of any one tool's interface.

The mistake that shows up most: dimensional weight

Referral fees are usually right — sellers know their category. The recurring error is the fulfillment fee, because it's set by size tier, and size tier is set by dimensional weight: length times width times height, run through a fixed divisor, then compared against actual scale weight, with the larger figure winning. Round a package dimension the wrong way during setup and Amazon can drop the product into a bigger, more expensive tier — and it stays there, charging every unit, every month, until someone catches it.

Full Circle has managed more than $500M in revenue across 100+ brands, and dimensional-weight misclassification is one of the most consistent line items we find when we audit fee statements inside that book of business — a mismeasured box quietly overcharging every unit shipped that month until someone checks the calculator's dimensions against the physical package Amazon actually has on file.

When the number doesn't match what Amazon actually charged you

A calculator gives you an estimate before the fact. Amazon's fee report gives you the actual charge after the fact. When they disagree, check in this order: is the size tier on the invoice the tier you expected from your entered dimensions; is the storage charge dated to the correct season, since October pricing applies the moment the calendar flips, not when you remember to update the field; and is the referral category the one Amazon's system assigned, which occasionally differs from the one you selected at listing.

If Amazon's own recorded dimensions are wrong — heavier or bulkier than the package that actually shipped — that's a fee dispute, not a math problem, and it's worth opening a case rather than just eating the difference. Amazon also ended its own FBA prep service on January 1, 2026, so if your calculator has a prep-fee field, that cost no longer defaults to zero — it needs a real number from wherever you're now sourcing prep.