Sample Size Calculator for Means

Determine the sample size needed to estimate a population mean

Standard Deviation (σ):

Estimate from pilot study or similar research

Margin of Error (e):

Half-width of confidence interval (same units as SD)

Confidence Level:

Population Size (optional):

Formula: n = (z × σ / e)²

Key insight: Halving the margin of error quadruples the sample size.

Tip: If σ is unknown, use range/4 or range/6 as an estimate.