A product with five sizes and three colors is not one item in your stockroom. It is fifteen, and each of them can sell out, pile up or go missing on its own. Stores that track stock only at product level often find out the hard way: the shirt shows 40 units in stock, but 31 of them are size XS and the size everyone wants has been gone for a week.
This guide covers how to set up variants so they can be counted, how to work out a size curve from your own sales, how to reorder by variant, and how to show sold-out options without losing customers.
Key takeaways
- A product total hides gaps. Plenty of stock overall can mean nothing in the sizes that sell.
- Not every option needs inventory tracking. Gift wrap or engraving choices are usually better handled another way.
- Split reorders by variant using a size curve from your own sales, corrected for stockouts.
- Reorder points work per variant, but supplier minimums often apply per product, so plan both.
- Keep sold-out variants visible and selectable, with a clear label and a way to be notified.
Why product-level stock is not enough
Most store platforms store inventory against each variant, but reports, dashboards and habits often roll it up to the product. That roll-up is fine for a quick look at total stock value. It is misleading for every decision about what to reorder, what to promote and what to discount.
Three things go wrong when you manage variants as one product:
- Best-selling sizes run out unnoticed because the product total still looks healthy.
- Slow sizes and colors accumulate because every reorder repeats the same split, regardless of what actually sold.
- Sales reports understate demand for popular variants, since a sold-out size sells nothing, and the next order is based on those low numbers.
Set up variants so they can be counted
One SKU per sellable combination
Each combination a customer can put in the cart (Blue / Medium, Blue / Large) needs its own SKU, its own stock count and, if you scan stock, its own barcode. Use a pattern that builds the SKU from the product code and the options in a fixed order.
| Part | Example | Notes |
|---|---|---|
| Product code | LS01 | Short, unique, never reused for a different product |
| Color code | BLU | Use a fixed list of color codes across the whole catalog |
| Size code | M | Use the same size codes everywhere: XS, S, M, L, XL |
| Full SKU | LS01-BLU-M | Same order for every product, so a list sorts sensibly |
A readable SKU helps during picking and counting. When a packer sees LS01-BLU-M on a bin label and on the packing slip, there is less room for error than with an internal number that means nothing to anyone.
Keep option order consistent
Decide once whether color or size comes first and stick to it on every product. It keeps admin lists, exports and spreadsheets in a predictable order, which matters when you are reviewing hundreds of rows.
Options that should not be variants
Some choices do not change what you pick from the shelf:
- Gift wrap, gift notes and engraving text are usually better handled as line item properties, add-ons or separate products, depending on your platform.
- Made-to-order options with no stock of their own can be set not to track inventory, so they never show as sold out by accident.
- Bundles should draw stock from their component variants where your platform supports that, or be managed carefully so a bundle cannot sell items you do not have.
Turning every option into a tracked variant multiplies the number of counts you have to keep accurate, and many platforms cap the number of variants per product.
Store and count by variant
Stock records are only as good as the physical stock behind them. A few habits make variant-level counts reliable:
- Give each variant its own labeled bin or shelf position, with the SKU on the label.
- Keep sizes in the same order on every shelf, smallest to largest, so a misplaced item stands out.
- Count variants, not products. When you check stock, record a count for each SKU rather than “about 40 shirts”.
- Count fast-moving variants more often. A size that sells daily drifts out of line with your records faster than a color that sells once a month. Our guides to cycle counting and ABC analysis show how to decide what to count and how often.
- Investigate mismatches straight away. A Medium recorded as a Large during receiving shows up as one variant short and another over, and both counts are then wrong.
Work out a size curve from your own sales
A size curve is the share of sales each size (or color) accounts for. It tells you how to split the next order across variants. Generic curves from other retailers are a poor guide; your customers, your fit and your product mix decide your curve.
Correct for days out of stock
The most common error is to divide units sold by the full period for every size, including sizes that were sold out for part of it. A size that sold out early will look less popular than it is.
Hypothetical example: a linen shirt in five sizes over the last 70 days. Size M was sold out for 14 of those days.
| Size | Units sold | Days in stock | Daily sales | Raw share | Corrected share |
|---|---|---|---|---|---|
| XS | 7 | 70 | 0.10 | 5% | 4.7% |
| S | 28 | 70 | 0.40 | 20% | 18.6% |
| M | 42 | 56 | 0.75 | 30% | 34.9% |
| L | 42 | 70 | 0.60 | 30% | 27.9% |
| XL | 21 | 70 | 0.30 | 15% | 14.0% |
| Total | 140 | 2.15 | 100% | 100% |
The raw share comes from units sold alone. The corrected share comes from daily sales on days each size was available. Medium moves from tied with Large to clearly the top size.
Use the curve to split an order
If the store plans to buy 120 shirts, the two curves give different orders:
| Size | Split by raw share | Split by corrected share |
|---|---|---|
| XS | 6 | 6 |
| S | 24 | 22 |
| M | 36 | 42 |
| L | 36 | 33 |
| XL | 18 | 17 |
The corrected split moves six units into Medium, the size that ran out last time. That is the size where a stockout costs the most.
Practical points:
- Use enough history. A few weeks of sales from a small store can be noisy. Combine similar products (all shirts from the same cut) if each one sells too little to show a pattern.
- Add waitlist signups. Requests for a sold-out size are demand your sales report does not show. Our back-in-stock notifications guide explains how to collect them per variant.
- Round with judgment. Small sizes often need a minimum presence even when they sell slowly, but avoid over-buying edge sizes simply to have every size in stock.
Reorder by variant
Reorder points per variant
A reorder point tells you when to order, and it should be calculated for each variant, not for the product. Our guide to reorder points and safety stock walks through the formula and three ways to set safety stock.
Order quantities per variant
A simple method for small stores is to decide how many days of sales each order should cover, then work out the target for each variant and subtract what you already have.
Hypothetical example: the same shirt, an order meant to cover 60 days of sales.
| Size | Daily sales | Target (60 days) | On hand | On order | To order |
|---|---|---|---|---|---|
| XS | 0.10 | 6 | 4 | 0 | 2 |
| S | 0.40 | 24 | 10 | 0 | 14 |
| M | 0.75 | 45 | 0 | 0 | 45 |
| L | 0.60 | 36 | 12 | 0 | 24 |
| XL | 0.30 | 18 | 9 | 0 | 9 |
| Total | 94 |
When the supplier sets the rules
Suppliers often set minimums per product, per color or per carton, not per variant. If the shirt above has a minimum of 120 units, you have to decide where the extra 26 go. As a rule of thumb, put them into the variants with the highest daily sales, where extra stock is least likely to sit. If the minimum would force you into sizes that already sell slowly, it may be worth asking the supplier about mixed cartons or a smaller first run.
Show sold-out variants clearly
When one size is out and others are in stock, the product page has to make that obvious without hiding the option.
- Mark the variant as sold out in the option picker, for example greyed out or with “Sold out” beside it.
- Let customers still select it, so they can see the status and sign up for a notification.
- Do not hide sold-out sizes entirely. Customers then assume you never made their size.
- Show the right photo and price for the selected variant, and make sure the add-to-cart button changes state when a sold-out option is selected.
- Preselect an in-stock variant by default rather than one that cannot be bought.
Our guide to sold-out and discontinued product pages covers what to do when a whole product is unavailable, and when it will not return. If a confirmed restock date is close and you want to take orders now, see preorders vs back-in-stock waitlists.
Dropping slow variants
Some variants never earn their place: a color nobody chooses, a size that sells once a season. Review them at least a few times a year.
- Stop reordering variants with consistently low sales unless they serve a clear purpose, such as completing a size range for a core product.
- Clear leftover units deliberately rather than letting them sit. Our guide on what to do with dead stock covers bundles, markdowns and other options.
- Remove or mark the variant as discontinued once it is gone, so it does not appear as a sold-out option that will never return.
Common mistakes
- Tracking stock at product level and noticing variant stockouts only when customers complain.
- Creating tracked variants for options that have no stock, such as engraving.
- Splitting every reorder evenly across sizes.
- Building size curves from raw sales without correcting for days out of stock.
- Hiding sold-out variants instead of labeling them.
- Inconsistent SKU patterns that make exports and counts hard to read.
FAQ
How many variants is too many?
There is no fixed number, and platforms set their own limits. The practical limit is how many counts you can keep accurate and how many choices customers can scan easily. If a variant rarely sells and is costly to stock, it is a candidate for dropping.
Should colors and sizes share one size curve?
Usually not. Track size and color separately at first, then look at combinations for your best sellers. A size curve for black may differ from the one for a seasonal color.
What if a variant has no sales history?
Start with the curve from similar products and review it after the first few weeks of sales. Order cautiously until a pattern appears.
Bottom line
Manage stock at the level customers buy: one SKU and one count per variant. Build size curves from days each variant was in stock, use them to split orders, set reorder points per variant and plan around supplier minimums. On the storefront, label sold-out options clearly and keep them selectable. Review slow variants regularly so the next order buys more of what sells and less of what does not.
