A search box is the highest-intent thing a shopper does on your site. They've stopped browsing and told you, in their own words, exactly what they're looking for. When that search comes back empty, you don't just lose a click — you lose the order, and unless something is logging it, you never even find out it happened.
There isn't one universal target number
A store with a narrow, well-labeled catalog will naturally see a lower zero-result rate than a store with a broad catalog and a lot of long-tail search terms. Rather than chasing a single benchmark figure, the more useful habit is watching your own no-result rate over 7, 30, and 90 days and treating a sustained increase as a signal something changed — a new product line without matching search terms, a seasonal spike in a term you don't stock, or a synonym gap that's been quietly costing orders for weeks.
The no-result list is the actual product
The rate itself is a summary. The list of specific searches that returned nothing is where the fixes live. Every zero-result search resolves into one of three actions, and all three take about the same amount of effort:
Add a synonym, so the term matches something already in the catalog — "trainers" resolving to the same results as "sneakers" is the classic example, and it can go one-way or both ways depending on whether the terms are truly equivalent.
Add a search rule, forcing a specific product, category, or page to the top for that term — useful when the catalog has the right product, but the general ranking isn't surfacing it.
Treat it as a stocking signal. If shoppers keep searching for something you don't sell, that's market research arriving for free.
A rhythm worth adopting
Stores that keep their zero-result rate low tend to review the no-result list on a fixed cadence — weekly is common — rather than only after a launch or a sales spike. Because rules and synonyms apply across every store on the same account, a synonym added for one storefront can be reused for the others in a couple of clicks, which makes the weekly review considerably less tedious than it sounds.
What to expect after a fix
A synonym or rule takes effect immediately — there's no reindexing delay to wait out. The honest way to check whether it worked is to watch that specific term drop out of the no-result list on the next report, not to guess from the overall rate, which moves slowly and is affected by everything else happening on the site at the same time.