Survey Sample Size Calculator
Work out how many survey responses you need to estimate a percentage within a chosen margin of error, with a finite population correction.
Updated · By Bibin XavierData 10 × 4
| Studytext · 10 levels | Effect_Size_dnumeric | SEnumeric | Nnumeric |
|---|---|---|---|
| Adams 2015 | 0.05 | 0.13 | 238 |
| Bose 2016 | -0.06 | 0.22 | 81 |
| Chen 2017 | 0.31 | 0.12 | 285 |
| Duarte 2018 | 0.18 | 0.15 | 177 |
| Eriksen 2018 | 0.25 | 0.13 | 229 |
| Fofanah 2019 | 0.75 | 0.31 | 41 |
| Gupta 2020 | 0.01 | 0.28 | 51 |
| Halvorsen 2021 | 0.14 | 0.2 | 97 |
Variables and options
Results
Calculated in your browserSample size for other margins of error
| Margin of error | 90% | 95% | 99% |
|---|---|---|---|
| ± 1% | 6,764 | 9,604 | 16,588 |
| ± 2% | 1,691 | 2,401 | 4,147 |
| ± 3% | 752 | 1,068 | 1,844 |
| ± 4% | 423 | 601 | 1,037 |
| ± 5% | 271 | 385 | 664 |
| ± 7.5% | 121 | 171 | 295 |
| ± 10% | 68 | 97 | 166 |
Note. Expected proportion 50%, large population.
Interpretation
With 385 completed responses, a result of 50% would be accurate to within ±5 percentage points, 95 times out of 100.
How to cite this tool
Using these results in a thesis, journal article, report or class assignment? Please cite this free tool so others can find it. It keeps the site free.
APA 7
Xavier, B. (2026). Survey Sample Size Calculator [Web application]. FreeStatisticalTools.com. https://freestatisticaltools.com/survey-sample-size-calculator/
BibTeX
@software{xavier_samplesizecalculator_2026,
author = {Xavier, Bibin},
title = {Survey Sample Size Calculator},
publisher = {FreeStatisticalTools.com},
year = {2026},
url = {https://freestatisticaltools.com/survey-sample-size-calculator/},
note = {Web application}
}Suggested sentence for your methods section: “The analysis was carried out with the free Survey Sample Size Calculator tool on FreeStatisticalTools.com (Xavier, 2026).”
What is a survey sample size calculation?
Work out how many completed survey responses you need to estimate a percentage within a chosen margin of error, and how many invitations to send at your expected response rate.
When to use a survey sample size calculation
Use it for descriptive surveys that estimate a percentage. For comparing groups or testing hypotheses, use the power analysis tool.
How to use this calculator
- Enter the values. Fill in confidence level, margin of error (%), expected proportion (%) and population size.
- Read the results. Results update automatically. Read the plain-English interpretation, then use Copy table to paste APA-style tables into Word and Copy for the results sentence.
Frequently asked questions
How many responses do I need for a 5% margin of error?
About 385 for a large population at 95% confidence, assuming a 50% proportion. Smaller populations need fewer.
Why use 50% as the expected proportion?
50% gives the largest required sample, so it is the safe choice when you do not know the likely result.
When does the population size matter?
Only when the sample is a sizable fraction of the population, roughly above 5%. The finite population correction then reduces the required sample.
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