Statistics

Survey response sample size Calculator

Estimate completed responses for a proportion with finite-population correction. This free survey response sample size calculator shows the calculation and its assumptions so you can compare your own figures.

Calculated on your device

Your results

Required Completed Responses385

Estimate completed responses for a proportion with finite-population correction.

Unlimited Population Responses385

Assumptions and estimates

Normal approximation for a simple random sample estimating a proportion; 50% is the conservative default. Enter zero population size for a large/unlimited population; otherwise finite-population correction applies. Extreme proportions, clustering, bias and nonresponse need adjusted designs; output is completed responses, not invitations.
Method: Uncorrected n=z²p(1−p)/e²; finite-population n=n₀/[1+(n₀−1)/N], rounded up.
Editable inputs are planning assumptions; check the method and result notes for scope.

Useful next steps

Use Compare options to test an alternative side by side.
Copy, print or download a record of this calculation when you need one.

Reports open your email app addressed to s@s1.ie with the public page address only. Your inputs are never added.

Remember favourites and recently used tools on this device

How the survey response sample size calculation works

Uncorrected n=z²p(1−p)/e²; finite-population n=n₀/[1+(n₀−1)/N], rounded up.

Editable inputs are planning assumptions; check the method and result notes for scope.

Using this calculator

Enter your own figures in the labelled inputs. Keep the currencies, units and time periods consistent.
Choose any applicable rate profile, pattern or assumption shown for this tool. Open additional inputs when relevant.
Review required completed responses and unlimited population responses, then read the stated assumptions and eligibility conditions before using the result.

Worked example

This is a static example using illustrative inputs, not facts about you or today’s date. The displayed eligibility selections and assumptions apply only to this example.

See example inputs

Confidence level: 95%
Required margin of error (percentage points): 5
Expected proportion (%): 50
Population size, zero for unlimited: 0

Required Completed Responses: 385
Unlimited Population Responses: 385

Mean, median & variation Calculator ↗Mean confidence interval, known SD Calculator ↗Linear regression & correlation Calculator ↗Independent event probabilities Calculator ↗

All statistics calculators →