Sample Size Generator

% The margin of error is the measure of how precise your estimate will be. A lower margin of error will require a larger sample size because this means that you desire higher precision. IPMVP suggests you strive for 10%.
% The confidence level is how certain you are that an estimate will fall within your desired precision range. A higher confidence level will require a larger sample size. Typically IPMVP requires 90%.
The population size is the total number of items you would measure if you had to measure all of them. For example, if you had 1,000 fixtures to calculate savings for at a confidence level of 90% and a margin of error of 10%, you would measure 64 fixtures. 1,000 fixtures is your population and 64 fixtures is your sample size.

Leave this as 50%

% For each question, what do you expect the results will be? If the sample is skewed highly one way or the other,the population probably is, too. If you don't know, use 50%, which gives the largest sample size. See below under More information if this is confusing.
Your recommended sample size is
377
  This is the minimum sample size required.

Alternate scenarios

Sample size: Confidence level:
Margin of error:
9.78%
6.89%
5.62%
Sample size:
267
377
643

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Code for calculations was provided by Shanti R Rao and Potluri M Rao, “Sample Size Calculator”

Raosoft Inc., 2009, https://www.raosoft.com/samplesize.html