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Sample size calculator
How many completed responses does your survey need? Or how precise is the sample you already have? Choose what to calculate and adjust the settings — the result updates as you type.
White = editable Gray = calculated or inactive
Advanced options
50% gives the largest sample requirement.
1 = simple random sampling; higher values increase variance.
Share of all invitations yielding an eligible, usable completion.
Required completed responses
385
95% confidence · 50% expected percentage · large / unknown population · design effect 1
Margin of error covers sampling uncertainty. It does not account for biased recruitment or unclear questions, and assumes random selection from the population.
For planning surveys that measure percentages, such as awareness, usage or satisfaction.
How this calculator works
The default expected percentage of 50% gives the largest sample requirement for the selected confidence level and margin of error. You can change it under Advanced options.
Uses a two-sided normal approximation for a percentage, with a finite-population correction when a population size is entered. Small samples and percentages close to 0% or 100% may require a different method. Design effect is an assumed variance adjustment, not a substitute for specifying the sampling design.
Margin of sampling error assumes probability sampling. For opt-in or quota samples, use the result as a planning benchmark. It does not account for recruitment bias or question wording. Precision applies to the group analysed, not automatically to each subgroup.
Need help planning a study? Our team designs and runs surveys across Indonesia, with reliable samples recruited through our own panel and partner network.
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