How does the funnel bottleneck finder work?
Borrowed from Reliability engineering: Series system: total = product of stage rates
Reliability engineers treat a chain of parts as a series system whose overall reliability is the product of each part. A funnel has the same structure, with conversion rates in place of reliabilities.
A one-point lift at a low-rate stage raises the total by a larger share than a one-point lift at a high-rate stage, which is why the lowest rate is usually the bottleneck.
Worked example
A US store gets 20,000 visits. Stage rates of 50%, 30%, 10% and 40% give 0.6% overall, or 120 sales. Lifting the 10% stage by one point adds 12 sales, while the same lift on the 50% stage adds 2.
How should I read my result?
Start here. Small changes at this stage change the whole result.
Test offers and page changes in order of expected lift.
The funnel is healthy. Look for volume instead.
Embed this calculator
Questions about funnel bottleneck finder
What stages should I include?
Use the steps your buyers take, such as visit, product view, cart and purchase.
Is a one-point lift realistic?
It is a common size for a single well-run test, though results vary.
Does order matter?
No. The product is the same in any order, but the lift depends on each stage's rate.