ACXPA · CX Hub
The Survey Sample Size Calculator that gets the maths right for every metric
Most contact centres report a CSAT or NPS off whatever responses came back. Work out how many responses you actually need for a result you can trust — or check how much the survey you already ran is really telling you. Pick your metric: the maths changes for each.
Everyone you could survey for this result — the list or population the score speaks for. Drag the slider to model a different size.
How far off the true score you can live with. Drag the slider to see the effect on the number you need.
The share you expect to score top-box (e.g. satisfied). The further from 50%, the fewer responses you need. 50% is the safe setting when you're not sure.
We'll turn the responses you need into how many customers to invite.
Optional. If you reward responses, we'll total the cost of the sample. Leave at 0 to skip.
Expected-split and standard-deviation overrides, the invites planner and the cost overlay are part of the Advanced calculator, included with ACXPA Business Membership.
Responses needed
Verdict
Coverage
of your base
Margin
points
Responses
needed
How much of your customer base you're hearing from
Worth knowing
Your customer base barely matters
What sets your accuracy is how many people respond, not how big your list is. It's the same reason a national poll can read a whole country from a couple of thousand people: once your base is comfortably bigger than the sample, making it bigger barely changes the answer. Drag the customer-base slider from a few hundred up to hundreds of thousands and watch the required number sit almost still.
Who replies matters as much as how many
That same poll falls apart if it only reaches one kind of person. Surveys are no different: if only your happiest or angriest customers answer, even a big sample misrepresents everyone in the middle. The maths here assumes responses are representative — a large but skewed sample is a confident wrong answer, not a safe one.
Method & assumptions
Included with your membership
You've got the full version,
, the advanced features on this calculator are unlocked with 's ACXPA Business Membership — split and spread overrides, the invites planner and the cost overlay.
The advanced calculator features are exclusive to Business Memberships
, the advanced toolkit is reserved for ACXPA Business Members and isn't part of 's Vendor Membership. Talk to us about access.
