Margin of Error Calculator

margin of error calculator

Determining the accuracy of your survey data has never been so simple! Voxco’s best-in-class Margin of Error Calculator allows you to measure the difference between your gathered survey results and the real views of your intended audience. While it’s not possible for survey results to perfectly match with the overall population, our handy tool will help to calculate the margin of error for ensuring the effectiveness of your survey.    

Calculate the margin of error for your survey

Population Size

Confidence Level (%)

Sample size


What does the margin of error mean?

A margin of error is the statistical amount of difference that can occur between the survey results and the overall population value for any research project. Being expressed in percentage, the margin of error plays a crucial role in every research project as the outcome of the survey relies on it. 

In other words, it is the key to measure the effectiveness of your survey. A small margin of error reflects more confidence in your survey results whereas a large margin of error represents more difference between your survey results and the views of your total population.   

Read more about the margin of error

How to calculate the margin of error for your survey?

margin of error calculator

In order to calculate the margin of error for your survey, you need to determine the following:

    • sample size 
    • population standard deviation 
    • The confidence level for the outcome  

Divide the population’s standard deviation (σ) by the square root of the sample size (n) and multiply the result with the value based on your desired confidence level (z).

What are the applications of the margin of error calculator?

margin of error calculator

Suppose you’re planning to launch a new product and you’re confused among the 2 options that you have i.e. Product A and Product B. Your target market comprises 500,000 prospective clients. This value is your total population.

You plan to survey 500 of those prospective clients. This value is your sample size.

After gathering the survey results, you discover that 65% of respondents prefer Product A. Now you should input the confidence level in the MoE calculator. The confidence level represents the certainty about the accuracy of the survey sample as compared to the attitude of the entire population. Usually, researchers prefer the confidence level at 95%. 

Once you input these numbers in the margin of error calculator, you’ll get a margin of error of 4%.

As 65% of your participants chose Product A, so this margin of error indicates that there’s a 95% of probability that 61% to 69% of your total population prefers product A for your new launch.

Understanding the role of sample size in the margin of error

By determining the margin of error, you can check if your survey’s sample size is appropriate or not. In case your margin of error is too large, you should increase the sample size of your survey. This helps to ensure that the attitudes of the surveyed participants match closely with the total population. With that being in mind, you need to start sending surveys to more people! 

Ensuring reliability in your survey data

margin of error calculator

Identify your total population right 

This includes the total number of people whom you want to study through your survey. The 500,000 prospective clients mentioned in our above example.  

Define the level of accuracy you’d like to achieve 

This includes measuring the margin of error as well as the confidence level of your sample. It depends on the risk that you’re ready to take that your responses will differ from your outcomes. 

Create the sample size 

Once you’ve successfully balanced the confidence level and the margin of error that you want to have, it’s time to determine the number of people you’d need to survey. It’s important to remember that everyone who receives your survey will not respond, so your sample size includes only the respondents who completed your survey.  

Evaluate your response rate 

This features the percentage of participants that actually responded to your survey among those who only received it. You need to review your previous surveys to determine the usual response rate. On sampling a random population, it’s estimated that around 10% to 15% of participants are likely to complete the survey.  

Read More About NPS


SURVEY METHODOLOGIES 15 Questions to use in your NPS Survey Template Maximize NPS Insights Unlock insights to drive growth, impr ...