Your supplier sends you "Basic T-shirt black S", "Basic T-shirt black M", "Basic T-shirt blue S"… each combination as a separate product. Your store, on the other hand, wants a single product page — "Basic T-shirt" — with its size and color variations. That translation, from simple products to a variable product, looks trivial until you do it by hand across an entire catalog. That's when the traps show up.
The problem: simple on the outside, variable on the inside
Suppliers export flat: one row per combination. Modern ecommerce thinks in variable products: a parent product with variations that share a description and images but differ in size, color, price or stock. To get from one to the other, someone has to decide which rows are really the same product. And that's where the mess begins.
Detecting what goes together (without getting it wrong)
Grouping correctly is most of the work. It's done by what the products share: a pattern in the name, a common parent SKU, the same base attributes. The risk lies at both extremes: grouping things that don't belong together (two different products with similar names) or splitting up things that do (the same T-shirt broken into two product pages). A good grouping proposal shows you what it has put together before touching anything, so you can confirm.
The rules almost nobody tells you about
Variable products have their own rules, and if you don't know them, they blow up in your face when you publish:
- The EAN goes on the variations, not on the parent. The variable product has no barcode of its own; each size/color does. Putting an EAN on the parent is a classic mistake.
- The parent's SKU can be left empty. WooCommerce allows it, and it's often the right call: the real SKU is on each variation.
- Each variation needs its own details: its image, its price and its stock. They aren't blindly inherited.
- Watch out for orphaned simple products: products that were already published on their own and that the new variable product is going to replace. You should be warned before they're overwritten: when the variable product is published, those simple products are deleted from the store to free up their SKUs.
Order matters: the image before the variation
A plumbing detail that makes all the difference: when publishing, each variation's image has to be uploaded before the variation is created or updated, as a single atomic step. Do it the other way around and you end up with variations without photos — that half-finished catalog where some sizes have an image and others don't. Doing it in the right order, and in one piece, is what prevents that silent disaster.
Why doing it by hand doesn't scale
A fashion or spare-parts catalog can have hundreds of variable products, each with dozens of variations: thousands of combinations, each with its own EAN, SKU, price and image in the right place. Doing it by hand while following every rule is slow and prone to errors you only discover when a customer tries to buy a size that doesn't exist. Automating the grouping — with your review on top — is what turns that nightmare into just one more step in the pipeline.