SKU profitability is what is left from one product’s sales after you take out every cost that product caused: Amazon fees, VAT, landed cost of goods, advertising, returns and storage. To get it right, you match each of those costs to the SKU that generated it, then divide by units sold. Amazon’s own Profit Analytics tool gives you a starting point, but it only becomes a true profit figure once you add your own costs and the items Amazon cannot see.
This guide shows you what to include, how to calculate it, where UK sellers most often get it wrong, and how to keep the numbers current without living in a spreadsheet.
TL;DR
- SKU-level profit means every revenue and cost line is attributed to the SKU that caused it: fees, VAT, ad spend, refunds, storage and landed cost.
- Amazon’s Seller Central reporting shows fees, sales, advertising and net proceeds per SKU, ASIN and parent ASIN, but it does not know your inbound freight, sourcing costs or off-Amazon advertising.
- UK-specific items such as VAT on seller fees, the digital services fee and the FBA fuel and logistics surcharge change the per-unit maths.
- Revenue is not profit: a product that sells well can lose money on every unit once ads, returns and storage are allocated to it.
- Monthly manual checks miss slow leaks. Automated, API-connected tracking lets you spot them while there is still time to act.
Table of Contents
- Why SKU-level profit matters more than account-level profit
- The cost lines every SKU needs
- UK fee changes that move your per-unit profit
- A worked example: one SKU, from price to profit
- The hidden margin leaks to look for
- What good looks like: margin benchmarks
- Using Amazon’s own reports
- Tax: why accurate records matter to HMRC
- Spreadsheet, Amazon reports or software?
- Our perspective: profit you can act on
- Setting up SKU profit tracking in six steps
- Where Osellpa fits
- FAQ
- Sources
Why SKU-level profit matters more than account-level profit
Your account total hides the truth. A healthy overall margin can be made up of three strong products carrying five weak ones, and from the top-line numbers you cannot tell which is which.
Working at SKU level answers the questions that actually drive decisions:
- Which products should get more ad budget, and which should get none?
- Which listings are worth restocking, and which should be sold through and retired?
- Is a price cut still profitable once Amazon’s percentage fees are recalculated on the lower price?
- Are returns or storage turning a good-looking product into a poor one?
It is also worth separating three levels that sellers often mix up. A SKU (your merchant SKU, or MSKU) is the code you assign. The FNSKU is Amazon’s label for a unit in its network. The ASIN is the product page itself, and a parent ASIN groups variations such as sizes or colours. Amazon’s tool reports at all of these levels, which matters because two SKUs can point at the same ASIN with different costs, for example when you bought two batches at different prices.
If you have searched for profit by ASIN or SKU-level profit, this is the same idea viewed at a different grouping. Pick the level that matches the decision: ASIN for listing and ad decisions, SKU or batch for purchasing and stock decisions.
The cost lines every SKU needs
The principle is simple. Per industry guidance on SKU-level tracking, you match every revenue and cost line to the SKU that generated it, using settlement data, product-level ad spend, refunds and storage allocation. Here is the full list for a UK seller.
| Cost line | Where it comes from | Common mistake |
|---|---|---|
| Selling price | Your listing price, net of VAT if you are VAT-registered | Using the VAT-inclusive price as revenue |
| Referral fee | Amazon, a percentage of the sale price | Forgetting it moves when you change the price |
| FBA fulfilment fee | Amazon, based on size and weight | Ignoring size tier changes after a packaging update |
| Storage and aged inventory charges | Amazon, monthly | Not allocating per unit |
| Advertising | Amazon Ads, per SKU or ASIN | Allocating spend evenly across the catalogue |
| Returns and refunds | Amazon, per SKU | Counting the sale but not the lost fees |
| Landed cost of goods | You: product, inbound freight, duty, prep | Using the supplier invoice price only |
| Other costs | You: software, packaging, off-Amazon ads | Leaving them out because they are not in Seller Central |
The last two rows are where most errors live. Amazon’s FBA Revenue Calculator is good for estimating fees, storage and fulfilment, but it does not account for costs outside Amazon such as inbound shipping, product sourcing or off-Amazon advertising. You have to supply those yourself.
UK fee changes that move your per-unit profit
UK sellers have had several changes to account for recently. If your SKU model was built a couple of years ago, check it against these.
VAT on Amazon fees. Since 1 August 2024, Amazon charges 20% UK VAT on seller fees (referral, FBA and storage) to UK-established sellers. If you are VAT-registered, that is input tax you reclaim, not a cost, so your profit model should treat fees net of VAT. If you are not VAT-registered, it is a real cost and your margin is lower than the fee table alone suggests.
Digital services fee. From 1 October 2025, the same source notes a 2% digital services fee on selling and FBA fees. On a low-value item that small percentage is visible in a per-unit view and invisible in a monthly total.
FBA surcharge. From 17 April 2026, a 1.5% fuel and logistics-related surcharge applies to FBA fulfilment fees in the UK and several European marketplaces. Amazon says it is reflected in its SKU Economics tool and Revenue Calculator, so compare any older spreadsheet against those.
Referral fees. Most UK category referral fees sit between 8% and 15%, with some categories different. Because the fee is a percentage of the offer price, a discount does not reduce your costs in proportion: the fixed FBA fee stays the same while your revenue shrinks.
Size and weight. Fulfilment fees depend on how Amazon measures your product. If you suspect a heavy fee on a bulky but light item, read our guide to dimensional weight and the 5,000 rule behind UK FBA fees.
A worked example: one SKU, from price to profit
The figures below are illustrative, chosen to show the method. They are not Amazon rates or a forecast for your category.
Imagine a kitchen product, not VAT-registered for simplicity, sold at £20.00:
- Selling price: £20.00
- Referral fee at 15%: £3.00
- FBA fulfilment fee: £3.20
- Landed cost (product, freight, duty): £7.50
- Advertising per unit sold: £2.40
- Storage allocated per unit: £0.30
- Returns allowance per unit: £0.60
Total costs: £17.00. Profit per unit: £3.00, a 15% margin on the selling price.
Now see what a small change does. Say you drop the price to £18.00 to win the Buy Box. The referral fee falls to £2.70, but everything else stays the same, so costs become £16.70 and profit per unit is £1.30. A 10% price cut has removed more than half your profit. That is the sort of relationship you cannot see at account level, and the reason a SKU view should be checked before any promotion.
The same logic applies to advertising. If that product needs £4.00 of ad spend per unit to hold its ranking, profit goes to a loss of £0.40 per unit even though sales look excellent.
What good looks like: margin benchmarks
There is no single right margin, but the same industry source gives a useful frame: established brands with pricing power can hold margins of 25% or more, while resellers and wholesalers typically sit closer to 10% to 15%. It also notes that a decline of around 10% in margin often signals hidden fees or overspending on ads.
Use those as reference points, not targets. What matters more is trend: a SKU at 14% that is steady is healthier than one at 22% that falls three points every month.
A practical way to classify your catalogue:
- Protect: high margin, good velocity. Keep stock deep and defend the Buy Box.
- Fix: good sales, thin margin. Check the price, the cost, the ad spend and the return rate.
- Fund: low sales, healthy margin. Test more ad budget or listing improvements.
- Exit: low sales and low margin. Sell through and do not reorder.
Using Amazon’s own reports
Seller Central gives you a decent first look for free. Profit Analytics combines sales, returns, fulfilment fees, advertising spend and your own cost data in a SKU-level view. The SKU Economics report lets you drill into fee buckets such as fulfilment, referral and storage without merging separate sales and ad reports by hand.
The limits are worth knowing:
- It depends on you entering and updating your cost of goods accurately for every SKU.
- It cannot see costs outside Amazon, such as freight invoices or off-Amazon promotion.
- It is a view, not an alert system. Nothing tells you when a SKU turns unprofitable between checks.
For a handful of products that is manageable. Beyond that, the admin builds up. The same industry guidance suggests manual reporting can take 4 to 8 hours per month per account, and that moving to tools which pull data through the Amazon SP-API and Advertising API gives near-real-time visibility.
Tax: why accurate records matter to HMRC
Profit is also what you are taxed on. HMRC taxes net profit after allowable business expenses, not gross sales, so recording fees, advertising, freight and other costs properly is useful beyond decision-making. Good SKU-level records make your bookkeeping cleaner too. For your own tax position, speak to a qualified UK accountant, particularly on VAT treatment and what counts as an allowable expense in your circumstances.
Spreadsheet, Amazon reports or software?
| Approach | Best for | Weak spot |
|---|---|---|
| Spreadsheet | A few SKUs, a hands-on seller | Manual exports, formula errors, time |
| Amazon’s own reports | Sellers who want a free baseline | No alerts, no off-Amazon costs, manual cost entry |
| Automated analytics software | Growing catalogues, heavy PPC, several marketplaces | Monthly subscription |
| Outside help | Sellers who want a review of strategy and margins | Cost, and finding the right fit |
If you are considering outside help with ongoing margin tracking and cost monitoring, an independent directory of Amazon marketing agencies can help you compare specialisms, markets and budgets before you speak to anyone.
Our perspective: profit you can act on
We built Osellpa because the same pattern kept appearing with Amazon sellers: plenty of data, very little clarity. Sales dashboards say one thing, ad reports another, and the settlement file a third. Putting them together by hand each month means that by the time you find a problem, it has been costing you for weeks.
Our view is that SKU profitability should be a live number, not a month-end exercise. That is why Osellpa connects directly to Amazon’s API and brings profit tracking, PPC management, inventory and alerts into one place. Automation matters most on the advertising side: when campaigns are managed against actual profit rather than ad-reported sales, there is less wasted ad spend. Some of our users report sales increases of up to 20% after adopting the tools, though results depend on your products, margins and how you act on the data.
We also think the tools should fit every seller. A part-time seller with 15 products and a large seller with thousands face the same question: which products make money? The answer should not require a weekend of spreadsheet work.
— Harry
Setting up SKU profit tracking in six steps
- List every SKU with its ASIN and fulfilment method. Include FBA and merchant-fulfilled products.
- Enter landed costs, not supplier prices. Add freight, duty, prep and any packaging.
- Decide your VAT treatment. Record fees and revenue net of VAT if you reclaim it.
- Pull ad spend by SKU or ASIN. Do not spread it evenly.
- Allocate returns and storage per unit. Use the actual month, not an annual average.
- Review weekly for your top SKUs, monthly for the rest. Set a margin floor and investigate anything that falls below it.
Where Osellpa fits
If you want SKU-level profit, PPC optimisation and alerts without the spreadsheet, Osellpa offers three plans: Launch at £10 per month (or £96 per year), Scale at £20 per month (or £192 per year) and Advanced at £40 per month (or £384 per year). You can compare what each includes on the Osellpa pricing page, or start from the Osellpa homepage.
FAQ
What is a SKU on Amazon?
A SKU, or stock keeping unit, is the unique code you give each product or variation you sell. It differs from the ASIN, which is Amazon’s product page identifier. One ASIN can be linked to several SKUs, for example when you hold stock bought at different costs.
How do I calculate profit per SKU on Amazon UK?
Start with the net selling price, then subtract referral fees, FBA or fulfilment fees, storage, advertising, returns and your landed cost of goods. Divide by units sold to get profit per unit. Amazon’s Profit Analytics covers the Amazon-side figures, but you must add costs it cannot see, such as freight and off-Amazon advertising.
Does Amazon show profit by ASIN?
Yes, to an extent. Profit Analytics and the SKU Economics report in Seller Central show fees, sales, advertising and net proceeds at SKU, ASIN and parent-ASIN level. The profit figure is only as accurate as the cost data you supply.
How often should I check SKU profitability?
Check your best-selling and most heavily advertised products weekly, and the rest of the catalogue monthly. Fee changes, price moves and ad spend can shift margins within days, so a purely monthly review can miss problems until they have already cost you money.
