Sample size calculator
Calculate the minimum sample size for statistically reliable results
Want to know in advance how many direct mail pieces you need to send to make reliable statements about response rates?
With this calculator, you can easily determine the right sample size based on your expected response, desired confidence level, and acceptable margin of error.
This helps you avoid sending too few mailings and drawing unreliable conclusions, or unnecessarily high costs.
Input
Adjust the values to calculate the sample size
Higher expected response → smaller sample size needed
Higher confidence → larger sample size needed
Percentage of expected response
Result
Minimum sample size
7,300
mail pieces
You need to send at least 7,300 mail pieces to estimate the response with 95% confidence within ±10% of the expected response.
This equals ±0.5 percentage point.
This result provides a good indication. We do not give any guarantee — small deviations may occur. Always consult our DM experts for the final outcome.