A shirt in four colours and four sizes: is that one product with sixteen variants, or four separate products? The answer changes a lot.
Merge into one product when…
- The difference is size or colour of the same item.
- Prices are close or identical.
- The customer compares options intending to buy one of them.
Merging pools reviews on one page instead of scattering them, and that alone lifts trust.
Split when…
- Each option has a different search audience — "men's perfume" versus "women's perfume".
- The price gap is wide enough to confuse the listing.
- You want a standalone page targeting a standalone search term.
Inventory is the operational deciding factor
Every variant carries its own stock. If you cannot track quantity per colour and size separately, variants will hand you wrong numbers and sales of items that ran out.
A recurring mistake
Creating variants for options that affect neither stock nor price — "would you like gift wrapping?". That is a custom field, not a variant, and making it one multiplies your inventory rows for no reason.