Sample Size Calculator

Sample Size Calculator

How confident you want to be that the actual data falls within the margin of error.
The acceptable range of error (e.g., 5% = +/- 5%).
If you know the total number of people in the group.

Required Sample Size:

0
Calculated using Cochran’s Formula
The Sample Size Formula

The Sample Size Formula

If you prefer to calculate it manually, use the standard formula for a single proportion:

n =
Z² · p(1 – p) e²
  • n: Required sample size.
  • Z: The Z-score corresponding to your desired confidence level.
    • 95% confidence = 1.96
    • 99% confidence = 2.58
  • p: The estimated proportion of the population with the attribute you are measuring. If unknown, use 0.5 (50%) to ensure the largest possible sample size.
  • e: The margin of error expressed as a decimal (e.g., 0.05 for ±5%).