Use this Sample Size Calculator to determine a sample size for testing the response to an upcoming B2B or B2C direct marketing campaign, or for a research survey in which you want to determine how many people to interview or send questionnaires (the minimum sample size).

The confidence level is expressed as a percentage and represents how sure you are that the actual percentage of the population who would respond lies within the percentage limit of error. The 95% confidence level means you can be 95% certain; the 99% confidence level means you can be 99% certain. Most researchers use the 95% confidence level. Greater confidence will generate larger sample sizes.

The percentage limit of error is the plus-or-minus error amount or deviation (expressed as a percentage) that you are willing to tolerate from your projected response rate. For example, if you enter a 2% response rate and are willing to accept an error (or deviation) in response of /- .3% (i.e., response between 1.7% and 2.3%) at a confidence level of 95%, your sample size will be 8,366.  Enter the percentage as a whole number and / or decimal (i.e., 10 or .1 for 10%, 1 or .01 for 1%, .001 for .1% of a percent, etc.)

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