Funnel Leak vs Funnel Bottleneck: What's the Difference?

A funnel leak is any point in the customer journey where prospects drop off rather than continuing to the next stage - the general, umbrella term for every place a funnel loses people, and most funnels have several of them at once.

A funnel bottleneck is the single stage losing the most people relative to how much traffic actually reaches it - the specific leak that matters most, and often not the one that's most visible or most discussed.

The distinction is one of scale versus priority. Every funnel has leaks throughout - it's common for a large share of prospects to be lost between each stage of a typical conversion funnel - so simply noticing that drop-off is happening somewhere isn't itself useful diagnostic information. A bottleneck is what narrows that broad picture down to where effort should actually go: the drop-off rate between stages, not the overall conversion rate, is what reveals where the real problem lives, since conversion rate alone confirms something is wrong without saying where. Bottlenecks are also rarely the last step in a funnel, since by the time a prospect reaches the final stage they've already survived every earlier filter - the stage worth fixing first is usually earlier, where the volume lost is largest. A small improvement to the biggest bottleneck typically moves overall conversion more than a large improvement to a leak near the end of the funnel, where too few people remain for any fix to matter much.