SKU: what counts as one, and how a tracked-SKU limit is counted
A SKU, short for stock keeping unit, is one distinct sellable item you hold stock of and reorder on its own: one size, one colour, one pack format. On Shopify that means one variant rather than one product, which is why a forty-product catalogue can quietly be two hundred SKUs.
What a SKU is
A SKU, or stock keeping unit, is one distinct item you hold stock of and reorder on its own. One size, one colour, one pack format, one flavour: each is its own SKU, because each runs out separately and each gets ordered separately.
The word does double duty, and both uses are correct. It names the unit of stock, and it names the code you put on that unit, something like CAND-SAND-8OZ. For inventory maths, the unit is what counts. Sales per day, days of cover, a reorder point, a suggested order quantity: every one of those numbers is calculated per SKU and nowhere else. Roll two sizes together and the maths stops meaning anything, because the 8 oz can be empty while the 4 oz sits on the shelf.
Why Shopify stores undercount
On Shopify the SKU is the variant, not the product. A merchant who says "I sell about forty products" is usually describing forty product pages. Open those pages and each one carries three sizes and two scents, and the real number you have to watch is far larger. Nothing in a storefront forces you to notice this, so the first honest count is often a surprise.
A worked example
Take a candle maker. One sandalwood candle in 8 oz, 4 oz and travel tin is three SKUs. A beeswax taper sold in a pair and a box of six, each in ivory and black, is four. A gift box with no variants is one. Three product pages, eight SKUs, eight reorder points.
Counting a three-product catalogue
| Product page | Variants | SKUs counted |
|---|---|---|
| Sandalwood candle | 8 oz, 4 oz, travel tin | 3 |
| Beeswax taper | Pair and box of six, ivory and black | 4 |
| Gift box | None | 1 |
| Total | Three product pages | 8 |
How a tracked-SKU limit is counted
Any tool priced per tracked SKU has to answer one question before it can charge you or alert you: which variants is it watching. The limit is a count of tracked SKUs, which means variants the tool holds stock, velocity and a reorder point for, not product pages and not supplier catalogue lines.
Restoc is built that way. Its three tiers are drawn around that count: Starter is $29 a month for up to 200 tracked SKUs, Growth is $59 for up to 1,000, Pro is $99 for up to 2,000. Paid a year at a time those are $290, $590 and $990, and every tier carries a 60-day free trial. The subscription is billed by Shopify on your Shopify invoice, not by a separate card payment.
Where the cap is applied
The cap is enforced on the server when your catalogue syncs, not as a soft warning after the fact. As a store's active SKU count approaches or passes its tier limit of 200, 1,000 or 2,000, the dashboard and the billing screen carry a banner showing current usage against the limit, with a direct prompt to move up a tier. The point is that the number is visible before a sync refuses the extra variants, rather than discovered later.
So the count matters in two directions. Too low a tier and variants fall outside the cap. Too high and you pay for room you do not use. Count your variants once, add the lines you expect to add over the next year, and pick on that number.
Related terms
The SKU is the unit. These are the numbers you calculate against it, each with its own entry.
- Sales velocity: units sold per day for one SKU, measured over a window of 7, 14 or 30 days.
- Lead time: the days between placing a supplier order for that SKU and the stock being sellable. Only you can supply it.
- Reorder point: the stock level at which the SKU needs ordering, built from velocity and lead time.
- Days of inventory on hand: current stock divided by velocity, read as how long this SKU lasts.
- Safety stock: the buffer you add on top of the reorder point for demand that spikes or suppliers that slip.
- Stockout: the SKU hits zero and the listing stops selling.
- Dead stock: a SKU you still hold and will never reorder, which should leave your watch list rather than your count.
- ABC analysis: a way of ranking SKUs so the ones carrying your revenue get the attention.
Questions
Is a SKU the same thing as a product?
No. A product is the thing a customer browses; a SKU is one sellable configuration of it. One product page with three sizes is three SKUs, because each size has its own stock level and its own reorder decision.
Is a SKU the same as a barcode or UPC?
No. A SKU code is internal: you invent it, you control its format, and it only has to make sense inside your business. A barcode such as a UPC or EAN is externally issued and shared across retailers. The same item usually carries both.
Does every Shopify variant count as a SKU?
For inventory purposes, yes. If Shopify tracks a separate inventory quantity for it, it runs out separately, so it needs its own velocity, its own lead time and its own reorder point. A product with no variants is a single SKU.
How many SKUs does a small store have?
It depends entirely on variant depth, not on how big the store feels. Forty product pages with five variants each is 200 SKUs; two hundred product pages with no variants is also 200. Count the variants to find out.
What happens if my store goes past a plan's tracked-SKU limit?
In Restoc the limit is enforced on the server at sync time, so variants beyond the cap are not taken on. Before and after that point, the dashboard and the billing screen show current usage against the limit with an upgrade prompt, so the shortfall is visible rather than silent.
Do multiple locations multiply my SKU count?
Not in the maths. A location adds another stock figure against the same SKU, it does not create a new one. Whether a tool charges or alerts per location is a separate question from how many SKUs you have.
Should a bundle get its own SKU?
If you order the bundle in ready-made, yes: it has its own stock and its own supplier wait. If you assemble it from components you already stock, the components are the SKUs you watch, because they are what you reorder.
What counts as an active SKU?
One you still sell and still intend to buy again. A discontinued line you are selling down does not need a reorder point, and leaving it in your watch list only pads the count and the noise.