Check every SKU's FBA size tier against your own measurements, and price each mismatch
Updated · By Ecomsellertool editorial team
To audit FBA size tiers, pull Amazon's recorded tier, dimensions and weight for each SKU from the Fee Preview report every week and compare them with your own measurements of a packed unit. Rules flag mismatches, price each one per unit and per month, and rank them. A person reviews the case and decides whether to request a remeasurement in Seller Central.
- From January 15, 2027, Amazon replaces two bulky tiers with four and the extra-large structure with six oversize tiers, and adds flat product and overhang handling fees (checked November 6, 2026).
- When your weight or dimensions differ from Amazon's, Amazon's information decides the fee, and Amazon says it may update that information from time to time.
- A fee reimbursement request must arrive within 90 days of the charge, with one claim per fee charge. Amazon says a remeasurement typically takes 10 days.
- The US Fee Preview report lists product-size-tier, the three sides and the weight. It can be up to 72 hours old, and through SP-API it can be requested once per day.
- In this recipe fixed rules do every comparison and calculation, a person measures the unit and decides each case, and no AI model is needed.
The step map: who runs each step
Trigger: A weekly schedule, a new SKU, a packaging or supplier change, or a new Amazon rate card with a known start date, such as January 15, 2027.
| Step | What happens | Who runs it |
|---|---|---|
| 1 | The workflow requests the Fee Preview and Storage Fees reports and stores each SKU's recorded tier, three sides, weight and expected fee with the date it read them. | Rule |
| 2 | A person measures and weighs one sealed unit the way Amazon describes, edge to edge with loose material extended, and records the numbers, the date and photos. This repeats only when the packaging or supplier changes. | Person |
| 3 | Rules work out girth, dimensional weight and shipping weight for both sets of numbers, then the tier each set falls in under the table for that date. | Rule |
| 4 | Rules match each difference to a row of the decision table, ignore differences that do not change a fee, and add SKUs close to a tier line to a watch list. | Rule |
| 5 | For each mismatch, rules price the fee on Amazon's record and on your measurement from the rate card, then multiply the difference by units shipped per month and rank the cases. | Rule |
| 6 | The top cases go to one queue with both sets of numbers, the monthly cost, any reason a remeasurement is blocked and the evidence on file. | Rule |
| 7 | A person checks the case, re-measures if it looks doubtful, and decides whether to request a remeasurement, change the packaging or leave it. | Person |
| 8 | After the request, the workflow reads the record again, logs what changed and alerts the owner when a recorded size or tier moves on any SKU. | Rule |
6 rule steps · 0 AI model steps · 2 person steps. A rule follows fixed logic you approve; an AI model handles messy input and its output is checked by rules; a person makes the calls listed below.
What stays with a person
- Measuring and weighing a sealed unit, and keeping the evidence
- Whether a mismatch is worth one of the account's monthly remeasurement requests
- Submitting each remeasurement request and any research request in Seller Central
- Packaging changes for SKUs close to a tier line
- Which price or margin change follows when a tier really does move
Which tools can run it
- A spreadsheet with the Fee Preview export, your measurements and tier formulas, run by hand, for under a hundred SKUs
- Zapier, Make or n8n calling the reports API on a schedule, writing to a sheet and posting cases to Slack
- Custom code on your accounts, for a large catalog, full rate cards, 2026 and 2027 tier tables, a case queue and history per FNSKU
Systems it connects
- Amazon Seller Central reports (Fee Preview, Storage Fees)
- Amazon Selling Partner API
- Your product or packaging spec sheet
- Warehouse, 3PL or prep center that can measure a unit
- Sales or shipment data for units per month
- Slack or email for the case queue
Build size: Medium
The comparison is simple; the work is keeping clean measurements per FNSKU, turning two tier tables and rate cards into rules, and handling kits.
A wrong size tier is easy to miss. A loose poly bag flap gets measured, or a supplier changes a carton, and a higher fee then repeats on every unit Amazon ships until somebody looks. This recipe is that look, on a schedule: Amazon's record on one side, your measurement on the other, every difference priced per month, and the worst cases in front of a person. It is one page of our automation library, and it is step 2 of our guide to Amazon's 2027 fee changes, written as a workflow.
It sits upstream of two neighbors. Our FBA reimbursements guide covers disputes once you have a case, and our finance and recovery agent checks fees already charged in settlements. This page checks the measurements those fees come from.
What does each mismatch mean, and what should you do about it?
Use this table as the rule set. Every row is a finding the weekly check can produce. The evidence column is our suggestion: the Amazon pages we read do not list what evidence a remeasurement request needs.
| What the data shows | Likely cause | What the rule does | What a person decides | Evidence to keep |
|---|---|---|---|---|
| Amazon's sides or weight are larger than yours, and the fee is higher | Loose bag, handle or bulge caught edge to edge; a batch that packed differently | Prices both fees, ranks by monthly cost, opens a case | Re-measure, request a remeasurement, or tighten the packaging | Dated photos of a sealed unit against a ruler and on a scale; the report row |
| Amazon's numbers are larger, but the tier and weight band stay the same | A small difference with no fee effect | Logs it; no case | Nobody | The log row |
| Amazon's numbers are smaller than yours | An old record, or your packaging grew | Flags a margin risk: shows the fee at your measurement; never opens a claim | Which number your margin model uses; whether to change the packaging | Your measurement and the packaging change date |
| The tier name changes on January 15, with the same measurements | The 2027 table, not an error | Reprices on the 2027 card; no case | Reprice, repack or accept | The tier table and rate card date |
| Both agree, but a side or the weight sits close to a line | A next batch may land on the other side | Adds it to a watch list, with the distance to the line | Whether to redesign the packaging | Packaging spec and tolerance from the supplier |
| Measurements match, yet the fee looks wrong | Price band, fee category, peak rates or surcharge, not size | Sends it to the fee check; no remeasurement | Finance reviews the charge | The settlement row |
| A kit, set or multipack differs | One item was measured instead of the whole packed set | Flags the SKU as a kit and blocks the case until re-measured | Who measures the packed set | Photo of the packed set and its component list |
| Correcting one side raises dimensional weight | A thicker record can move the weight band | Prices the corrected record before any case opens | Whether the net saving is worth a request | Both calculations |
| The mismatch is real, but no request is possible | No available units, two remeasurements in 60 days, or the monthly limit used | Holds the case with the reason and the next possible date | Send units, or wait for the next month | The case record |
Amazon's own guidance supports the watch list row. Its item package page names packaging close to a size-tier threshold, loose bags, movable handles and soft items that bulge among the most common causes of discrepancies (checked November 6, 2026). It also says sensors measure packaging edge to edge, so measure a sealed unit as a customer would receive it, with loose material extended. A measurement taken any other way will not match, and the difference will not be Amazon's mistake.
What does a mismatch cost per SKU?
Price the fee both ways, then multiply. Keep it per month so that cases can be ranked against each other.
Monthly cost of a mismatch = (fee on Amazon's record − fee on your measurement) × units shipped per month
The SKUs, sizes and volumes below are made up, not client results. The fees are real rows from Amazon's 2027 non-peak rate card for non-apparel at the $10 to $50 band, and the oversize handling fee page, both checked November 6, 2026. Amazon's 3.5% fuel and logistics surcharge on fulfillment fees is not included.
| Made-up SKU | Amazon's record | Your measurement | Fee on the record | Fee on your measurement | Difference | Units a month | Monthly cost |
|---|---|---|---|---|---|---|---|
| Boxed kitchen tool | 10 by 8 by 2.5 in: large standard, 1.25+ to 1.5 lb | 10 by 8 by 1.6 in: large standard, 12+ to 16 oz | $5.57 | $4.67 | $0.90 | 600 | $540 |
| Storage set, 4.9 lb | 18.5 by 7 by 5 in: small bulky, 4+ to 5 lb | 17.75 by 7 by 5 in: large standard, 4.75+ to 5 lb | $9.07 | $7.80 | $1.27 | 200 | $254 |
| Flat panel, 30 lb | 62 by 26 by 3.5 in: small oversize, 40+ to 41 lb, flat product fee | 62 by 26 by 4.25 in: small oversize, 49+ to 50 lb | $33.82 | $27.94 | $5.88 | 40 | $235 |
| Flat 7 oz item | 8 by 5 by 0.9 in: large standard, 4+ to 8 oz | 8 by 5 by 0.7 in: small standard, 6+ to 8 oz | $4.01 | $3.97 | $0.04 | 900 | $36 |
Three things in that table are easy to miss. A dimension can cost more than the scale weight: the kitchen tool's extra thickness lifts its dimensional weight two bands, while its real weight never changes. Handling fees change the sum: the flat panel's thicker true measurement removes the $8.40 fee but adds $2.52 in fulfillment fee, so the net saving is $5.88. And the last row shows how rate cards reorder the queue. On the 2026 card, the same two rows differ by $0.41, or $369 a month at that volume. From January 15, 2027, the gap is $0.04, and that case may not be worth a request.
The figure looks forward. Amazon's reimbursement policy says it will reimburse FBA fees when it confirms inaccurate weight or dimensions, on requests made within 90 days of the charge, with one claim per fee charge (checked November 6, 2026). The page does not explain how an amount is worked out across past charges, so we do not forecast one. To size the leak beside your other gaps, our Amazon brands page has a table of them.
Why check every week, and not once?
Because the record can move without you doing anything. Amazon's dimensions page says it may verify weight and dimensions using representative samples, may change its information from time to time, and calculates fees from its own information at the time the fee is calculated (checked November 6, 2026). So a SKU that was right in March can be wrong in June, in either direction. Reading the record weekly is a small job for software. A person only measures again when the packaging or supplier changes.
Once the baseline exists, the weekly job is a difference check against last week's record. Any change to a recorded side, weight or tier raises an alert, whether or not it changes the fee today. Our supplier cost change recipe can then pick up the new fee and recheck margin, and a new SKU can start clean if measurements are captured in your new SKU setup.
Which Amazon fields does the check read?
Two reports carry Amazon's record. The Fee Preview report gives longest-side, median-side, shortest-side, length-and-girth, the weight, your-price and product-size-tier, plus estimated fees, and its data can be up to 72 hours old. Amazon's SP-API report documentation lists it as GET_FBA_ESTIMATED_FBA_FEES_TXT_DATA, for sellers' FBA inventory with active offers, available once per day per seller, needing the Pricing and Amazon Fulfillment roles (both checked November 6, 2026).
Check the field names when you build. The help page calls the weight item-weight, and the API documentation calls it item-package-weight, and it lists expected-fulfillment-fee-per-unit and expected-future-fulfillment-fee-per-unit for the US store. We read the documentation, not a live report, so run one and map what actually comes back. The Storage Fees report, GET_FBA_STORAGE_FEE_CHARGES_DATA, is the cross-check: it has the same sides, the weight, product_size_tier and a fulfillment_center column.
What changes on January 15, 2027?
Standard-size lines stay the same. Bulky and extra-large lines do not, so products there can change tier with no change to the product. These side limits come from Amazon's product size tiers page, which applies the 2026 table through January 14, 2027 (checked November 6, 2026). All sides are longest, median and shortest, in inches. The same page points to a new Fee Change Comparison dashboard in Profit Analytics for the product-level view, which we have not seen because it needs a signed-in account. Our fee post has the rest of the calendar.
| Tier | Through January 14, 2027 | From January 15, 2027 |
|---|---|---|
| Small bulky | 37, 28, 20 | 28, 24, 20 |
| Medium bulky | Does not exist | 37, 28, 20 |
| Large bulky | 59, 33, 33 | 52, 28, 28 |
| Extra-large bulky | Does not exist | 59, 33, 33 |
| Oversize | Four extra-large weight tiers | Six tiers: small, medium, large and long oversize, special oversize light and heavy |
Notice that the name is the trap. A product with a 30 inch longest side is small bulky today and medium bulky on January 15, with no change on your side, so a rule that stores only the tier name will read it as an error. Store the sides, and let the rules work out the tier from the table for that date. The new handling fees run off the sides too. Amazon's oversize handling fee page applies the flat product fee to oversize items with a shortest side under 4 inches and a median side of 25 inches or more, and the overhang fee above a 43 inch median side.
How do you get cases through the remeasurement limit?
Treat requests as a budget. Amazon's item package page says the monthly limit is set per account from the number of offers with inventory, is shown under the widget you find by typing "remeasure" in the search box, and resets on the first of each month. An FNSKU can be remeasured twice within 60 days at most, and Amazon asks you to submit only requests you believe will change your fees (checked November 6, 2026). So work from the top of the ranked list, and hold anything you are unsure of until a person has measured it again.
Between now and January 15 there are three monthly counts: November, December and January. A remeasurement typically takes 10 days and needs a sellable unit in a fulfillment center, so a SKU that is out of stock waits. Plan the first pass soon, especially for bulky and oversize items. The request can also go against you: Amazon's measurement governs, and a request may confirm the record. For the filing steps and the 90-day clock during peak, see the finance and recovery agent.
Which tool should run it?
| Level | Fits when | What to watch |
|---|---|---|
| A spreadsheet with the Fee Preview export and tier formulas | Under a hundred SKUs, mostly standard-size | Someone must re-export it; two tier tables and rate cards live in formulas |
| Zapier, Make or n8n with the reports API | A few hundred SKUs, a sheet as the record, cases sent to Slack | Report requests run in stages, and failures need to be visible; log every run |
| Custom code on your accounts | A large catalog, kits, bulky items, history per FNSKU, one case queue | Can run on Ecomsellertool Growth OS beside your other Amazon data, reading through SP-API |
No AI model is needed. Every step is a comparison, a lookup or a multiplication, and that is why the result can be trusted and checked. If you want the fee difference inside your contribution margin, the rate card used here is the same one a margin check needs.
Who builds an FBA size tier audit?
Ecomsellertool builds workflow automation on your own accounts, and we have built on Amazon's seller APIs since 2017. For this recipe we agree your measuring method and cost threshold, load your spec sheet, then connect the reports, rate cards and one case queue. Your team measures and decides every request. Send a project brief, or see how our workflow automation service works.
None of our case studies is a size tier audit project. These are the parts we have shipped that it reuses:
- A fee engine on Amazon's reports. For SellerDrive we built scheduled data retrieval and a fee calculation engine that computes fees Amazon does not provide, from predefined rules, with total fees drawing on reports such as
fba_storage_feesandfba_estimated_fees. - Fee overcharges as a case type. The reimbursement system we built for Execuseller includes refunds for overcharged FBA fees, such as weight and size discrepancies.
- Kits mapped to components. Cheddy handles kits, multipacks and single-pack ASINs against the components in a warehouse, which is the mapping a set needs before it can be measured.
What did we not check?
We read the Amazon help pages and report documentation linked above on November 6, 2026, for the US store only, and Amazon can edit them. We did not see a live report or the remeasure widget, which needs a signed-in seller account. Amazon's pages do not state what evidence a request needs, or how much of a past charge comes back, so we make no claim on either. Dimensions here are made up, and this is not financial advice.
Get your size tier audit built
Send us your catalog size, tiers and who can measure a unit
Describe the workflow you want automated. We reply with a written plan: scope, timeline and a fixed price.
Frequently asked questions
How do I find out what size tier Amazon has for my product?
Download the Fee Preview report in Seller Central and find the product by its FNSKU. The product-size-tier field shows the tier, next to the longest, median and shortest sides and the weight. Amazon says the data can be up to 72 hours old. The Monthly Storage Fees report is a second place to read the dimensions Amazon used.
What do I do if Amazon has the wrong size tier for my FBA product?
Check the numbers in a fee report, then measure a sealed unit the way Amazon describes, with loose material extended. If you still believe the record is wrong, type remeasure into the Seller Central search box and follow the widget. Amazon's measurement decides the fee, so a request can confirm the record instead of changing it.
Can I get a refund if Amazon charged me on the wrong size tier?
Amazon says it will reimburse FBA fees if it confirms they were charged using inaccurate weight or dimensions, if you ask within 90 days of the charge. Each fee charge gets one claim. The policy page does not explain how an amount is worked out across past charges, so this recipe does not forecast a refund. It prices the cost going forward.
Do the 2027 bulky and oversize tiers change my size tier?
They can, even when nothing about the product changes. From January 15, 2027, small bulky is capped at a 28 inch longest side instead of 37, and large bulky at 52 instead of 59. Extra-large is replaced by six oversize tiers. Standard-size lines stay the same. Re-run your measurements against the new table and rate card.
How is dimensional weight calculated for FBA?
Amazon divides the unit volume in inches, length times width times height, by 139. For bulky and oversize items it assumes a minimum width and height of 2 inches. Dimensional weight counts when it is larger than unit weight for large standard, bulky and oversize items, except special oversize heavy. Small standard uses unit weight.
How often should I check FBA dimensions?
Read Amazon's record weekly, because Amazon says it may update measurements from time to time and reading a report changes nothing on your account. Measure the physical unit only when something changes: a new SKU, new packaging or a new supplier. Run a full pass before a new rate card starts, so there is time for remeasurements that typically take 10 days.
How many remeasurement requests can I make?
Amazon sets a monthly limit per account, based on the number of offers with inventory, and shows it under the remeasure widget. The count resets on the first of each month. Each FNSKU can be remeasured only twice in 60 days. Amazon asks you to submit only requests you believe will change your fees, which is why this recipe ranks cases by cost.
