Conversion Rate Confidence Interval Calculator
A conversion rate measured from a sample is an estimate, not a fixed truth. Enter your visitors and conversions and this returns the confidence interval: the range your real conversion rate is likely to fall in, plus the margin of error either side. A rate with no interval around it can quietly mislead you, especially on small samples.
What is the true range of your conversion rate?
This uses the Wilson score interval, which stays accurate even when the sample is small or the rate is near 0% or 100%, unlike the simpler textbook (Wald) formula that can hand you impossible bounds like a negative rate. Read the result as: if you repeated the same test many times, the true conversion rate would sit inside this range on the stated share of occasions. A wide interval is the tool telling you to gather more data before you trust the headline number.
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