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Learn how many participants you should recruit for your study. |
This article applies to: UserTesting
On this page:
- How many participants do I need?
- Sample size considerations
- Estimate your sample size
- Sample size recommendations
How many participants do I need?
See our short video for information on sample sizes.
Sample size considerations
Consider the following to determine the optimal number of participants for your test:
Test type
- Depending on your test type, you might consider a different number of participants.
- For instance, a benchmark study might need more participants than an early-stage concept test.
See the table below for recommendations based on the type of test you are building.
Testing goals
- What are the goals of the test?
- For instance, if you’re trying to identify glaring usability issues, a sample size of 5 may be enough.
- But if you want to go deeper to find more issues, use larger sample sizes, like 15 participants.
Decision-makers
- With whom will you be sharing the insights?
- Do you need a certain sample size to be persuasive to your decision-makers?
Confidence levels
- Depending on the approach, you might need sufficient data to build confidence around surfacing themes.
- Exploratory (80%) – Best for qualitative tests, like prototype, concept, or usability in design/development.
- Industry norm (90%) – Best for higher stakes quantitative usability testing and surveys.
- Publication (95%) – Best for publishing in academic journals or political polls.
- Life or death (99%) – Best if bad decisions lead to injury or death.
- Read more about how confidence and intervals can impact your sample size.
Availability
- The UserTesting Network offers broad coverage in the US, UK, and Canada - including niche audiences.
- In other markets like Australia, France, India, Mexico, Spain, and Germany, reaching niche audiences may be slightly harder.
- Our Audience Solutions team is always available to help find your target audience through our partner networks regardless of where you’re testing, but you may consider adjusting your sample size based on availability.
Surveys and interaction tests
For most surveys and interaction tests, the default of 100 participants is a good starting point, but you should customize it based on your needs. Sample size depends on multiple factors including, but not limited to:
- The type of feedback being collected (for example, observational vs. single metric vs. comparison).
- The total size of the population being tested (for example, general population vs. internal employees).
- Decision-maker expectations.
- Your acceptable confidence level and margin of error (see tables below).
Note: To activate AI themes for surveys, you need at least 20 participants to complete the survey.
Estimate your sample size
You may find online calculators to help you determine how many participants to invite to your test. When choosing a sample size calculator, it's important to keep in mind the methodology you plan to use. Here are some calculator resources we recommend:
- MeasuringU – Find sample size calculators for your use case, including testing against a criteria or benchmark and discovering problems in a user interface.
- Qualrics—The calculator at the top of this blog applies to surveys, but the rest of the post helps you understand the formula behind calculating sample size.
We have also created some tables below to help you consider sample sizes for different study types.
Sample size estimates for binary UX metrics (e.g., task success)
|
Margin of Error (+/-) |
90% Confidence |
95% Confidence |
| 20% | 15 | 21 |
| 15% | 28 | 39 |
| 10% | 65 | 93 |
| 5% | 268 | 381 |
Sample size estimates for comparing metrics (e.g., A/B testing)
|
Difference to 90% confidence |
within subjects |
between subjects |
| 50% | 17 | 22 |
| 35% | 29 | 64 |
| 20% | 50 | 150 |
| 10% | 115 | 664 |
Sample size recommendations
Our research experts at UserTesting recommend the following sample sizes based on your study type, goals, and approach.
Note: These sample sizes are just recommendations. Keep in mind the margin of error and confidence level your study is willing to accept. The industry standard is a 90% confidence level, but your study may call for a different percentage.
Benchmarking
Ideal sample size
- Qualitative: 10-20 participants
- Quantitative: 30-40 participants
Description: Baseline existing experience and measure progress on a regular cadence over time.
How do we do it at UserTesting? Participants complete key tasks and rate their experience regularly (monthly, quarterly, semi-annually, or annually). Rating questions can be industry-standard (SUS, SUPR-Q) or custom informal metrics defined by an organization.
Best-in-class analysis
Ideal sample size
- Qualitative: 10 participants
- Quantitative: 30 participants
Description: Gather insights on highly-rated and well-known experiences to understand how to emulate in your own experience.
How do we do it at UserTesting? Participants complete key tasks on "great" experiences.
Card sorting
Ideal sample size
- Qualitative: 30 participants
Quantitative: 50-60 participants
Description: Understand how and why people group and label related items or information to inform navigational structure and organization.
How do we do it at UserTesting? Participants "think aloud" as they sort items, concepts, etc. into categories. Tests may be open (participants name the categories) closed (the user defines categories for participants) or hybrid (some categories are predefined, but more can be added by participants).
Case study
Ideal sample size
- Qualitative: 1-4 participants
- Quantitative: N/A
Description: Build a story around an individual to establish thinking around a potential hypothesis that merits further investigation.
How do we do it at UserTesting? Participants are asked questions about their experiences, impressions, or preferences, or to interact with one or more interfaces to provide feedback.
Competitive testing
Ideal sample size
- Qualitative: 10-15 participants
- Quantitative: 30-40 participants
Description: Understand participant preferences between competitive experiences (ease of use, understandability, visual appeal, etc.).
How do we do it at UserTesting? Each participant completes key tasks on a single competitive experience. Responses to rating scale questions (like SUS, SUPR-Q) and performance metrics are compared across competitors.
Concept testing
Ideal sample size
- Qualitative: 5-8 participants
- Quantitative: N/A
Description: Gauge people's reactions to new ideas or concepts with or without a design to view or interact with.
How do we do it at UserTesting? Participants view or comment on a concept. A concept could be just a description or an experience to view or interact with.
Copy testing
Ideal sample size
- Qualitative: 8-10 participants
- Quantitative: 30 participants
Description: Learn whether copy is clear, effective, and aligned with organizational or brand values and goals.
How do we do it at UserTesting? Participants read copy and are asked to describe, provide commentary on their perceptions, or rate aspects of the language or messaging. Research objectives might include resonance, understandability, or clarity, among others.
Email copy and design
Ideal sample size
- Qualitative: 8-10 participants
- Quantitative: 30 participants
Description: Get feedback on email subject lines, content, layout, clarity, etc.
How do we do it at UserTesting? Participants view subject lines and email messages and are asked to comment on comprehension, clarity, appeal, tone of voice, visual design, and/or other elements.
Field studies
Ideal sample size
- Qualitative: 10 participants
- Quantitative: N/A
Description: Understand behaviors and/or needs in someone's natural environment.
How do we do it at UserTesting? Participants turn on the front-facing camera using our mobile recorder to record real-life experiences.
Image testing
Ideal sample size
- Qualitative: 8-10 participants
- Quantitative: 30 participants
Description: Determine whether the message or intent of imagery, their perceptions, and whether it is effectively communicating value is understood.
How do we do it at UserTesting? Participants view the image and are asked to describe, provide commentary on their perceptions, or rate aspects of the image. Research objectives might include clarity, visual appeal, or comprehension and/or other attributes.
Interviews
Ideal sample size
- Qualitative: 15 participants
- Quantitative: N/A
Description: Gather impressions, attitudes, expectations, and/or goals through a self-guided test or live conversation.
How do we do it at UserTesting? Participants are asked questions about their impressions, attitudes, expectations and/or goals in a self-guided test or live conversation.
Longitudinal/Diary study
Ideal sample size
- Qualitative: 15 participants
- Quantitative: N/A
Description: Understand people's behaviors and needs over a period of time.
How do we do it at UserTesting? Participants record multiple interactions over a period of time. The experience could be across channels or on a single channel.
Omnichannel and crosschannel
Ideal sample size
- Qualitative: 8-10 participants
- Quantitative: N/A
Description: Capture the experience as participants move between channels to accomplish a goal.
How do we do it at UserTesting? Participants record interactions on more than one channel. May require use of all recording solutions: desktop, mobile (on-screen and front-facing camera).
Preference testing
Ideal sample size
- Qualitative: 5-8 participants
- Quantitative: 100 participants
Description: Gain confidence in the alternatives you want to test by asking people to interact with and comment on each option. Also, understand why one version "won" over another by asking people to interact with and comment on the options tested.
How do we do it at UserTesting? Participants complete activities as they think aloud, along with rating scale questions to gauge or "measure" their experience.
Prototype testing
Ideal sample size
- Qualitative: 5-8 participants
- Quantitative: N/A
Description: Observe people as they interact with an early version of a design or experience.
How do we do it at UserTesting? Participants view a prototype on Figma, Axure, Dropbox, or some other publically accessible URL. Could be static or interactive.
Social networks
Ideal sample size
- Qualitative: 8-10 participants
- Quantitative: 30
Description: Gather insights on people's perceptions and behaviors as they view and interact with social posts.
How do we do it at UserTesting? Participants view a brand or company's presence on a social network and are asked to complete tasks and answer questions related to comprehension, clarity, appeal, tone of voice, and/or other elements.
Surveys
Ideal sample size
- Qualitative: N/A
- Quantitative: 100 participants
Description: Collect feedback from high sample sizes via a questionnaire.
How do we do it at UserTesting? Participants complete a questionnaire for observational, comparison, or single metric feedback. Sample size depends on the total size of the population being tested, your acceptable confidence level and margin of error, and decision-maker expectations.
Tree testing
Ideal sample size
- Qualitative: N/A
- Quantitative: 100 participants
Description: Learn whether or not people can find what they need within a web navigation.
How do we do it at UserTesting? Participants "think aloud" as they complete a task that asks them to find a destination within a navigation "tree". The ability of participants to find the right destination reflects how well the information is organized and named.
Usability testing
Ideal sample size
- Qualitative: 5-8 participants
- Quantitative: 30-40 participants
Description: Observe people as they complete tasks to identify what's working well and where they stumble.
How do we do it at UserTesting? Participants complete activities and tasks. A larger sample size can be used to test high-risk or complex applications if previous work has yielded inconclusive results and if you need to ensure that you uncover all potential barriers (15 contributors to find 90% of problems, 50 contributors to find 98% of problems).
Video testing
Ideal sample size
- Qualitative: 8-10 participants
- Quantitative: 30 participants
Description: Learn whether people understand content and value being communicated and/or find it appealing
How do we do it at UserTesting? Participants view video content and are asked to comment on comprehension, clarity, appeal, tone of voice, visual design, and/or other elements. They may also speak to calls to action, expectations versus reality, or complete tasks.
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