Amazon Seller Fees and Repricing: How to Calculate the Right Price Floor
Most FBA sellers who set a minimum price have done the basic arithmetic: what did I pay for this, and what do I need to cover it? That is not the same as the correct minimum price. Amazon takes a referral fee as a percentage of your selling price. FBA charges a fulfilment fee per unit by size tier, now with a surcharge on top. Storage accrues monthly whether you sell or not, and roughly triples for the fourth quarter.
Miss any of those and your floor sits below break-even. Get them all and you find something most fee guides never mention: the correct floor is not one number. It changes four times a year.
TL;DR
Your floor needs four numbers, not one, because Amazon's peak fulfilment window and its peak storage window do not run on the same dates. The fees that belong in a minimum price are the referral fee as a percentage of the selling price, the FBA fulfilment fee by size tier, the 3.5% fuel and logistics surcharge on that fee, per-unit storage, and prep or inbound cost. The formula divides fixed costs by (1 − referral rate − target margin rate). In the worked example below the same product carries a floor of $20.88 from mid-January to September, $21.88 in the first half of October, $22.39 through the fourth quarter, and $21.39 in the first fortnight of January. That is a $1.51 per-unit spread on one SKU.
Every Fee That Belongs in Your Minimum Price
Five cost lines belong in every FBA minimum price, and sellers routinely count two of them.
Referral fee. A percentage of the total selling price, including any shipping you charge. It varies by category and comes off the top before you see anything.
FBA fulfilment fee. A fixed amount per unit set by size tier and, since January 2026, by price band as well. It does not scale with your price, so it hurts most on cheap items.
Fuel and logistics surcharge. 3.5% of the fulfilment fee, applied since 17 April 2026. It is a multiplier on a number that is already moving, which is why it gets missed.
Storage. Charged per cubic foot of average daily inventory, monthly, at one rate for most of the year and a much higher one from October to December.
Prep and inbound. Prep centre charges, inbound freight, and placement fees are part of landed cost per unit, not overhead.
Leave one out and the floor is wrong. A repricer enforcing that floor will compete hard for the Buy Box at a price that does not cover what the sale actually costs you.
Referral Fees: What Amazon Actually Takes
The referral fee is charged on revenue, not profit, so it scales with every price move your repricer makes.
At 15% on a $20 sale, Amazon takes $3.00 before anything else, regardless of what you paid for the product. Amazon publishes the full schedule on its public referral fee table. Common US categories:
Two things to take from that table. The spread is far wider than most guides suggest, running from 3% on the portion of a watch sale above $1,500 up to 45% on Amazon device accessories, with most general merchandise sitting at 15%. And the banded categories are a repricing trap: a price cut that crosses a threshold moves you into a different rate. In Clothing, dropping from $20.50 to $19.99 takes the rate from 17% to 10%, which helps. Moving the other way does the reverse.
There is a minimum referral fee of $0.30 per item in most categories, but not all. Grocery and Gourmet and Media carry no minimum, and Fine Art has its own. Check your own category rather than assuming.
FBA Fulfilment Fees at 2026 Rates
Fulfilment fees are fixed per unit, so their effective cost rate rises as your price falls. That is the opposite of how sellers tend to think about them.
A product costing $4.60 to fulfil is a 23% cost rate at a $20 price and a 46% cost rate at $10. Repricing downward without accounting for that is where margin quietly disappears.
Since 15 January 2026 the US standard-size rates split by price band as well as by weight. Non-peak rates, per unit, excluding the 3.5% surcharge:
Small standard
Large standard
These are non-apparel rates, and they are the standard rates. Holiday peak rates apply from 15 October 2026 to 14 January 2027, adding an average of about $0.32 per unit. Then multiply whichever fee applies by 1.035 for the surcharge.
Size tier is set by the packaged product's dimensions and its unit or dimensional weight, whichever is greater. The step from small standard to large standard is where floor calculations most often break: a packaging change that pushes a product from 14 oz to 17 oz moves it between tables entirely, and nothing in your repricer notices.
Storage: Monthly, Peak, and the Aged Inventory Surcharge
Standard-size storage runs at $0.78 per cubic foot from January to September and $2.40 from October to December. That is more than three times the rate, not "slightly higher in Q4".
Convert it to a per-unit cost before it goes anywhere near a floor:
Per-unit storage = cubic feet per unit × monthly rate × expected months in storage
A product measuring 0.05 cubic feet that sells within two months costs about $0.08 per unit in storage at the standard rate. Small, but on an $8.00 item that is still 1% of revenue, and it quadruples if those two months fall in the fourth quarter.
The aged inventory surcharge is separate, and it starts earlier than most sellers think. It applies from 181 days in fulfilment centres, not 365. The first bands are confirmed at $0.50 per cubic foot from 181 to 210 days, $1.00 from 211 to 240, and $1.50 from 241 to 270, escalating from there. Published figures for the older bands disagree with each other, and the structure changed again in January 2026, so confirm your own exposure in Seller Central rather than working from a table.
Either way, the surcharge is a signal to clear inventory, not a cost to build into a normal floor. Once a SKU is accruing it, the right move is a clearance floor above zero margin rather than a target-margin floor. Peak also changes your competitive set, which is a separate job: the Q4 repricing settings guide covers the rule changes that go with the recalculation.
The Correct Formula, Worked Across All Four Windows
Referral fee and target margin are both percentages of the selling price, so they belong in the denominator, not added to your costs.
Minimum price = (landed cost + fulfilment fee with surcharge + storage + prep) ÷ (1 − referral rate − target margin rate)
The inputs, stated in full so the arithmetic can be checked: a Home and Kitchen product, large standard, 12 to 16 oz, selling in the $10 to $50 band, so a $4.60 fulfilment fee. Sourcing $8.00. Prep and inbound $0.50. Volume 0.20 cubic feet, averaging two months in FBA. Referral 15%. Target margin 20% of selling price.
Run it four times, because the fee calendar has four states:
Checking the first row at $20.88: referral $3.13, fulfilment $4.76, storage $0.31, prep $0.50, sourcing $8.00. Total cost $16.70, profit $4.18, margin 20%.
The two middle rows exist because the windows do not align. Peak storage starts on 1 October but peak fulfilment does not start until 15 October. Peak storage ends on 31 December but peak fulfilment runs to 14 January. A seller who recalculates once, in either direction, is wrong for a fortnight at each end.
The spread across the year is $1.51 per unit on a single SKU. At 300 units a day across the 92 days of the fourth quarter, the difference between holding the standard floor and holding the correct peak floor is about $41,700 of margin on one product.
A seller setting this floor at $18.00 by adding costs informally is below break-even in every one of the four windows.
Profit Protection runs this calculation from your stored cost inputs and enforces the floor on every pricing event, rather than holding a number you typed. One seller review on Capterra puts the dependency well: a genuine per-SKU net profit figure only appears once every relevant cost has been entered, rather than revenue being mistaken for profit. The full repricing feature set is worth a look alongside it.
Keeping Floors Accurate When Fees Change
Amazon's annual rate card is announced in October for January, and that is only one of the dates that moves your floor.
The 2026 cycle makes the point. Amazon announced the new rates on 15 October 2025 for a 15 January 2026 effective date, giving at least 90 days. Then on 17 April the 3.5% surcharge arrived outside that cycle entirely. Then the peak rates took over on 15 October. A floor reviewed once a year catches the first of those three.
The process when a change lands:
Identify which fee moved and which size tiers, price bands or categories it touches.
Pull the affected ASINs from the Fee Preview report in Seller Central under Reports, then Fulfilment by Amazon.
Recalculate with the new inputs, using the denominator formula rather than adding costs up.
Update floors before the effective date, not after.
The operational problem is scale. Across hundreds of ASINs, a fee change means recalculating every floor by hand, twice a year, forever. Floors derived from cost inputs move on their own when an input changes: update the fee once and every ASIN using it recalculates. The repricing rules guide covers the wider design principle.
If you are configuring this for the first time, Repricer's getting started guide recommends running Safe Mode, its simulation environment, for the first seven days so the rules run against live competitor data without changing real prices. The free trial itself is 14 days; Safe Mode is a setting you control, not a fixed phase. Details are on the plans and trial page.
On whether it is safe to let software move prices at all, Repricer states that it is compliant with Amazon's rules and guidelines, is a member of the Amazon Marketplace Developer Council and an Amazon Web Services Technology Partner, and works with Amazon directly as the platform changes.
Key Takeaways
Five cost lines belong in a floor, not two: referral fee, fulfilment fee, the 3.5% surcharge on it, per-unit storage, and prep or inbound.
Referral fees run from 3% to 45%, not the narrow band most guides quote, with most general merchandise at 15% and banded categories changing rate when your price crosses a threshold.
The $0.30 minimum referral fee is not universal. Grocery and Gourmet and Media carry none.
Fulfilment fees now split by price band as well as weight, so a price move can change the fee itself, and peak rates apply from 15 October to 14 January.
Storage is more than three times higher in Q4, at $2.40 per cubic foot against $0.78.
The aged inventory surcharge starts at 181 days, not 365, and is a signal to clear rather than a line to build into a normal floor.
The correct floor is four numbers, not one, because the peak fulfilment and peak storage windows start and end on different dates. In the worked example the spread is $1.51 per unit.
Action Plan
Confirm the size tier and price band for every ASIN you reprice. The fulfilment fee is wrong if either is wrong, and the price band can move when your repricer moves.
Confirm the referral rate for each category, including whether you sit near a banded threshold and whether your category has a minimum fee at all.
Calculate per-unit storage from your product's cubic feet and realistic months in FBA, and calculate it twice, at $0.78 and at $2.40.
Apply the 3.5% surcharge to the fulfilment fee. If your floors predate 17 April 2026, none of them carry it.
Build all four floors per ASIN and diary the four switch dates: 1 October, 15 October, 1 January and 15 January.
Check which ASINs are past 120 days in FBA so you can act before the 181-day surcharge starts rather than after.
Move to cost-calculated floors so the next rate change updates every affected ASIN from one input.
Frequently Asked Questions
1. Which Amazon fees belong in my repricing minimum price?
Five: the referral fee as a percentage of selling price, the FBA fulfilment fee for your size tier and price band, the 3.5% fuel and logistics surcharge applied to that fulfilment fee, per-unit storage based on cubic feet and months held, and prep or inbound cost per unit. Sellers who count only sourcing cost and the fulfilment fee typically set floors well below their true break-even.
2. How do I calculate the correct minimum price?
Divide your fixed costs by one minus your referral rate minus your target margin rate: (landed cost + fulfilment fee with surcharge + storage + prep) ÷ (1 − referral rate − target margin rate). Adding the percentages to your costs instead of putting them in the denominator understates the floor every time, because both scale with the price you are solving for.
3. Does my floor really need to change four times a year?
If you hold stock through the fourth quarter, yes. Peak storage runs October to December while peak fulfilment runs 15 October to 14 January, so there are two fortnights where one applies and the other does not. In the worked example above the four floors range from $20.88 to $22.39 on the same product.
4. When does the aged inventory surcharge start?
At 181 days in a fulfilment centre, starting at $0.50 per cubic foot and escalating with age. The older framing of a long-term storage fee at 365 days is out of date, and the band structure changed again in January 2026, so confirm your current exposure in Seller Central. Treat it as a prompt to clear the inventory rather than a cost to carry in a target-margin floor.
5. How often does Amazon change its fees?
The fulfilment and storage rate card changes annually, announced around October with at least 90 days' notice and effective in January. On top of that, peak rates apply every year from mid-October, and 2026 added a 3.5% surcharge in April outside the annual cycle entirely. Two reviews a year, in early October and again in late December, catch all of it.
