Classic tool
Sample Size Calculator
Estimate how many responses you need for a survey, poll or study using margin of error and confidence level.
Use this sample size calculator to estimate how many responses you should collect before reviewing a survey, poll, questionnaire or quantitative study. It is useful for marketing, UX research, support analysis, education and any project where you want enough data to make decisions without overspending time or budget.
Enter your target margin of error, confidence level and expected response proportion. If you already know the full population size, you can add it to apply the finite-population correction and get a tighter target. If the population is very large or unknown, simply leave that field blank.
The result gives you a practical minimum response target, the large-population baseline and a quick summary of the assumptions used. That makes it easier to plan recruitment, fieldwork, deadlines and reporting before your survey goes live.
Use clear inputs to get a more useful result.
How to use Sample Size Calculator
Open the tool, fill in the fields with the data you already have and generate the result step by step. If you want to compare scenarios, change one field at a time so it is easier to understand the impact of each value.
When Sample Size Calculator is useful
The goal here is simple: Estimate how many responses you need for a survey, poll or study using margin of error and confidence level. It works well for quick checks, planning, study and review before you move to a final decision or document.
What to review before using the result
Check units, labels, numbers, timing and any context that can change the meaning of the output. If the result will be used in a quote, technical task, published page or report, finish with a manual review.
Frequently asked questions
What should I prepare before using the tool?
Keep the key values, labels and units ready before filling in the fields. Cleaner inputs make the final result easier to review and compare.
Can I test different scenarios on the same page?
Yes. The safest approach is to change one field at a time, compare the outputs and note which value actually changes the final answer.
Is the result ready to use without checking it?
It is better to treat it as support. Review the output once more before using it in a quote, document, spreadsheet, technical task or published page.