3-step guide on how to calculate the margin for error when using a sample size calculator

Need to know the margin of error for your survey calculations? No problem – use a sample size calculator to calculate the sample size, population size, margin of error, and confidence level! 

Follow this easy 3-step guide of how to calculate margin of error!

If you are trying to figure out the right sample size to use compared to your overall population to learn more about your target market, then coming up with confidence level, the margin of error, sample size, and population as a whole is key. After all, you want to avoid asking too many people the questions that can skew the results, and you want to avoid talking to just a few people – if you keep the sample size too small, this can mean that you do not get a broad picture of your target market as a whole. The same goes for a sample size that is too big -although bigger is better since you get more answers, if you ask people that are not in your target market, this can give you inaccurate data. So how do you calculate the precise sample size and margin of error by using a sample size calculator?

There are a few ways they can easily calculate a margin of error using a sample size calculator. This way, you won’t have to choose the wrong sample size for your survey. When it comes to calculating the margin of error, typically you have to find the sample size and the sample portion. If you are using a sample size calculator you will already have the sample size. 

  • To calculate the sample proportion, you will have to figure out many people within your already-calculated sample size that have the same interests or beliefs. 
  • After calculating the sample proportion, you will multiply the sample proportion by ( 1 minus the sample size proportion). After completing this question, you will divide your answer by the sample size. For example, if your sample proportion is 5 and your sample size is 4, then you will go like this. Ex: 1 – 5 = -4 / 4 = -1
  • Once you have calculated the number, you will then take the square root of the answer that you have calculated. 
  • Once you have the square root, this number is called the standard error. This is the potential for error within your sample size that can lead to issues within your survey.
  • Once you have called the standard error using your sample size calculator, you can then multiply the answer that you have just received by the z-value for the confidence level. The confidence level is the number of times that you conduct the survey and the results are accurate – for example, if you conduct a survey 100 times and you find that the results were accurate 95 out of 100 times, then your confidence level is 95%. This is the confidence love and the z-value – however, keep in mind that when using the z-value in this equation, you have to use the precise table to transform the percentage into the z-value. If you are using the 95 confidence level margin for your equation, then you will find that this correlates to a z-value of 1.96.


Although this can be slightly confusing, you can use your sample size calculator to come up with the right sample size, confidence level, and margin or error – making it easy to calculate everything regarding your survey size!