Sample Size Confidence Interval Calculator Calculate Confidence Interval Calculate Sample Size Sample Mean Standard Deviation Sample Size (n) Confidence Level 90% 95% 98% 99% Margin of Error Standard Deviation Confidence Level 90% 95% 98% 99% Calculate Reset Population Size (Leave blank if very large): Confidence Level: 90% 95% 99% Margin of Error: % Estimated Proportion: % Calculate Reset Required Sample Size Confidence Level: Margin of Error: Population Size: