If you select a 95% confidence level then 95 out of 100 samples will contain the true population value.

Sample Size Calculator

This calculator determines the sample size necessary to estimate a population proportion within a specified margin of error.

Step 1. How many people are there in the population you are choosing your sample from? If unsure use 25,000. The built-in finite population correction factor will decrease the sample required if the population is small.
    What is the population size?
Step 2. The margin of error determines how close to the population proportion you would like the estimate to be (for example, +/- 5%).
    What margin of error can you tolerate?
Step 3: A confidence level of 95% establishes an interval that would be expected to contain the true value at least 95% of the time. Common choices are 90%, 95% or 99%.
    What level of confidence would you like?
>Step 4: If you have a previous estimate of the population proportion enter it here. Use a value between 0 and 100%. It is best to use 50% if unsure.
    What is the best estimate of the population proportion?
Sample Size you would need to achieve your goal
If your sample size is your margin of error would be