Customer Satisfaction Questionnaire: What Sample Size Do I Need for the Survey?



I am currently working on a Customer Satisfaction Questionnaire. I would be really grateful if somebody could please explain to me how I can calculate the most reliable (but feasible) sample size for my survey! Apologies for my ignorance! :)

Don Winton

…please explain to me how I can calculate the most reliable (but feasible) sample size for my survey!
There is an extensive discussion of sample sizes Sampling Plans.


I was better but I got over it.

Al Dyer


I'm not a fan of customer satisfaction surveys, in the past my highest return rate was about 15% and those that responded were the ones that usually had an axe to grind.

As to the sample size aspect, I would suggest that all customers be addressed, this is not an area where sampling would be effective. There would be too much bias in such a system that the results would not give you a true picture of customer satisfaction.

I would like to hear from other forum members if they have had positive results with customer satisfaction surveys.

My concerns are as follows:

Who in the customer structure do you send the survey? Managers, Quality, Engineering, Floor personnel?????

Does the person you send it to even know your product line?

Does the person you are sending it to have 20 similar requests from other suppliers?

Did the person you are sending it to have a fight with thier spouse last night and is in a bad mood?

I could go on with the variables but there are much better methods of determining customer satisfaction. Be creative and make it work for your organization, the methodology is up to you!

(PPM/Delivery/Cost/Responsiveness/Audit Results/Repeat Business/New Business/etc...)


Stan Hilliard

Hi Paola,

You could choose a sample size by considering its effect on the margin of error. Check out "Audit Sample Planner" at:

Stan Hilliard


Thank you everybody for your advice and suggestions!

I probably should have been more specific as to what we are doing. The survey will most probably be conducted through telephone interviews and the people we are going to target are members of our association, who have recently been in contact with our Customer Relations dept.

The survey basically aims at obtaining feedback on the service provided by this department (as to accuracy, courtesy, professionalism, competence etc. etc.). In this respect, if the questionnaire is structured properly, I think we should be able to collect interesting information!
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