**Instructions:** This calculator finds the minimum sample size required to estimate a population proportion (p) within a specified margin of error. Please select type the the significance level (\(\alpha\)) and the required margin of error (E), along with an estimate of the population proportion if one exists, and the solver will find the minimum sample size required:

More information about the *minimum sample size required* so you can better use the results delivered by this solver: In general terms, the larger the sample size n, the more precise of an estimate can be obtained of a population parameter, via the use of confidence interval. In this case specifically, use the formula for the margin of error of a confidence interval for a population proportion \(p\):

So, it can be observed from the above formula that if the sample size n increases (which is in the denominator), the margin of error \(E\) will decrease, provided that that the critical value \(z_c\) and \(\hat p\) do not change. So, the formula for obtaining the samply obtained by taking the above equation and solve for n.