Analytics and measurement
Conversion Rate Calculator with Confidence Range
Work out a conversion rate and the range it could plausibly sit in, given how much traffic stands behind it.
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For GA4's session key event rate, count sessions in which a key event happened, not the total number of key events.
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How to use
- Enter the number of conversions.
- Enter the sessions, visitors or clicks they came from.
- Add revenue if you want revenue per visit as well.
- Read the rate and its range, and check the note on which definition of conversion rate you used.
What it checks and how it works
Conversion rate is conversions divided by visits. The range is a Wilson score interval, the method the Wikipedia article on binomial proportion confidence intervals describes, at the confidence level you pick. It is wide when the base is small and narrows as traffic grows, which is why a rate of 4% on 100 visits and 4% on 10,000 visits are not the same evidence.
Definitions differ between tools. Google's dimensions and metrics reference defines GA4's session key event rate as sessions with a key event divided by all sessions, and Google Ads defines its rate over ad interactions that can be tracked to a conversion. Use one definition on both sides of any comparison. If conversions exceed visits, the rate passes 100% and the range is left out, because the interval needs conversions to be at most the visits.
Sources
- Google Analytics Help: Analytics dimensions and metrics opened 29 Oct 2026
- Google Ads Help: Conversion rate, definition opened 29 Oct 2026
- Wikipedia: Binomial proportion confidence interval (Wilson score interval) opened 29 Oct 2026
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Questions
About this tool
It depends on the industry, the offer and what you count as a conversion, so this tool does not give a benchmark. Compare your own rate across time and across segments, using the same definition each time.
A rate measured on a small number of visits can move a lot by chance. The range shows how far the true rate could plausibly be from the one you measured.
Yes, if you count every conversion and one visit can convert more than once. Google Ads notes the same for its own rate. Count converting sessions instead if you want a rate that stays at or below 100%.
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