Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Sample Size Calculator

Calculate the minimum number of respondents needed to estimate a population proportion within a given margin of error at a chosen confidence level — the standard formula behind almost every survey, poll, and quality audit. Includes the finite-population correction so you can plan surveys of small populations without over-sampling.

Population Size

Confidence Level

Margin of Error (%)

Fill in the required fields to see your result.

Probability

Confidence Interval Calculator

Computes the range of values likely to contain a true population mean at your chosen confidence level. Use it when reporting survey results, clinical trial outcomes, or any estimate derived from a sample.

Sample Mean

Sample Standard Deviation

Sample Size (n) (observations)

Confidence Level

Distribution Type

Fill in the required fields to see your result.

Key differences

	Sample Size Calculator	Confidence Interval Calculator
Category	Statistics	Probability
Inputs required	3	5
Result	Required Sample Size	Margin of Error (±)
What it does	Calculate the minimum number of respondents needed to estimate a population proportion within a given margin of error at a chosen confidence level — the standard formula behind almost every survey, poll, and quality audit. Includes the finite-population correction so you can plan surveys of small populations without over-sampling.	Computes the range of values likely to contain a true population mean at your chosen confidence level. Use it when reporting survey results, clinical trial outcomes, or any estimate derived from a sample.