A confidence interval for a population proportion is a range of values that is likely to contain a population proportion with a certain level of confidence.

The formula to calculate this confidence interval is:

Confidence interval = p +/- z*(√p(1-p)/n)

where:

p: sample proportion
z: the z-critical value based on the confidence level
n: sample proportion

To find a confidence interval for a population proportion, simply fill in the boxes below and then click the “Calculate” button.

p (sample proportion)

n (sample size)

Confidence level

95% C.I. = [0.4627, 0.6573]

You can be 95% confident that the interval [0.4627, 0.6573] contains the true population proportion.