Estimate the margin of error for a survey percentage using sample size, confidence level, and your expected proportion. Then build a survey and collect responses in minutes.
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This calculator estimates margin of error for a single proportion using a standard z‑score confidence level approach.
Number of completed responses.
Common defaults: 95% for most business surveys.
Use 0.50 if you’re planning a survey.
Example: 0.62 means 62%.
Margin of error is the “plus/minus” range around a survey percentage at a chosen confidence level. It’s often used to communicate the uncertainty from sampling.
When planning, using 0.50 is a common conservative default because it yields the largest margin of error for a given sample size.
Increase sample size, or segment less aggressively (small segments have larger uncertainty).
Our guide explains what margin of error really means, how to interpret it, common mistakes to avoid, and practical examples.
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