Having lots of products in your catalogue is only an advantage if the customer manages to reach the one they're interested in without getting frustrated along the way. Poorly designed category filters can make someone abandon a store with exactly what they were looking for, without ever having seen it.
Filters that reflect how the customer thinks, not how the warehouse is organised
It's common for a store's filters to reflect the catalogue's internal structure (brand, reference, supplier) instead of how the customer actually searches (size, colour, price, use). Designing filters around the questions a shopper asks themselves, rather than how inventory is organised, greatly improves navigation.
Too many filters at once
Showing twenty filter options all at once, most irrelevant to that specific category, overwhelms more than it helps. The most useful filters for that specific category should be at the top and visible, leaving the rest collapsed or accessible with one extra click.
Filter combinations that lead nowhere
Allowing filter combinations with no associated products (a size and colour that never coincide in stock, for example) creates an empty, frustrating page. Hiding or visually disabling combinations with no results before the customer selects them avoids that dead end.
An unhelpful default sort order
Sorting by "most recent" or alphabetically by default rarely helps with deciding. Sorting by relevance, popularity or rating by default, while leaving other options available but not as the starting point, usually makes the purchase decision much easier.
Frequently asked questions
How many filters are reasonable for a product category?
There's no fixed number, but four to six genuinely relevant filters for that category is usually more manageable than showing every possible catalogue attribute at once.
Do filters also affect the store's SEO?
Yes, if implemented as indexable URLs (for example, a specific URL for "blue t-shirts size M"), they can generate pages that rank for very specific searches, as long as there's enough stock and content to justify it.
Is it worth redesigning filters if the store is already selling reasonably well?
Yes, especially if the catalogue has grown over time: filters designed for a small catalogue tend to fall short as the number of products increases, and reviewing them periodically stops them from becoming a silent obstacle.