UX Research Sample Size Calculators. Helpful tools to estimate the right number of participants for surveys, card sorting and usability testing:
✅ Usability tests with 5 people cover 85% of usability issues.
✅ Interviews require 12–30 people to uncover most user needs.
✅ Start small: with 15–25 users as long as you can afford it.
✅ 40-users guideline is most likely to lead to reliable results.
✅ Surveys: aim for confidence level 95%, margin of error 2–5%.
✅ With 10.000 users, you will need ≥567 answers to reduce bias.
✅ Assume the response rate of 20–30% (incl. no-show-rate).
✅ To get reliable results, you will need to invite 2835 people.
✅ Card sorting: test with 15 users.
✅ Quantitative studies: test with 20 users.
✅ Concept testing: test with 10 users.
✅ Diary study: test with 20 users.
Useful resources:
Qualitative Sample Size Calculator, by UserInterviews
https://lnkd.in/enNhnjmZ
Survey Sample Size Calculator
https://lnkd.in/eSTAVcCz
Sample Size Calculator For Problem Discovery, by Jeff Sauro
https://lnkd.in/ebejHnKb
System Usability Score (SUS) Calculator
https://lnkd.in/eyeU9vtS
User Research Incentive Calculator, by UserInterviews
https://lnkd.in/dZim2YSq
Bonus: Design System ROI Calculator, by Knapsack
https://lnkd.in/eYCxBTGt
How Many Participants For a UX Interview?, by Maria Rosala
https://lnkd.in/eAEq6amb
Sample-Size Recommendations, by Raluca Budiu, Kate Moran
https://lnkd.in/erRN2RsW
Why You Only Need to Test with 5 Users, By Jakob Nielsen
https://lnkd.in/eqkb4mFN
Of course these numbers aren’t always reliable and will heavily depend on the UX research project. Don’t ask for big buy-ins — ask for small commitments instead. Start small, analyze as you go and establish a structured way to shape the design process.
UX research doesn’t have to be expensive or time-consuming. In the worst case, ask for 5×45 mins interviews with 5 users to discover critical issues and unmet user needs. Record short screen recording snippets and make them visible in the company.
Once you have built confidence in the work that you are doing, it will be much easier to ask for bigger commitments — in fact, you might be surprised by how quickly your research work will be requested, rather than merely applied to design work.