# Size Guide [Image] This experience supports a moment of confirmation. Shoppers arrive here when they are close to buying and want to reduce the risk of choosing the wrong size. For the business, this moment matters because clear sizing guidance can prevent hesitation, lower returns, and protect trust at the point of commitment. We tested Nike’s size guide page for men’s tops to see how shoppers interpret sizing information and decide whether it helps them move forward. Participants were asked to imagine shopping for a product and use the size guide to assess fit. The test used Satisfaction, Success, and Comprehension metrics to observe how easily users could find sizing details, understand the information presented, and feel about the experience overall. Sizing breakdowns rarely come from missing data—they come from uncertainty at the decision edge. This kind of testing helps teams see where clarity is doing its job and where confidence still slips. For product and business leaders, these signals highlight whether an experience is simply informative or truly supportive of forward momentum in high-impact purchase moments. * * * ### **Define Goals for Your Size Guide** An eCommerce size guide should balance user needs like clarity, trust, and confidence with business goals such as reduced returns and higher conversion confidence. Users want reassurance that they’re choosing the right size without guessing or overthinking. Businesses want to prevent fit-related frustration after purchase. When size guidance works, it replaces hesitation with certainty. **Audience:**
 This concept was tested with sporty consumers and online shoppers in the United States who used Nike’s product size guide while evaluating apparel and footwear. Participants were asked to consult the guide, interpret sizing information, and share whether it helped them feel confident choosing a size. **User Needs** At this moment, users are trying to avoid a wrong decision. The experience should support clear, confident judgment. - The guide should clearly explain how to choose the right size for the product (insightful). - The layout and instructions should be easy to follow without confusion (usable). - Measurements and recommendations should feel accurate and trustworthy (credible). - Users should be able to find and use the guide quickly without interrupting shopping flow (efficient). - The experience should help users feel confident and in control of their choice (empowering). Together, these needs ensure size guidance reduces uncertainty instead of adding friction. **Business Goals** From the business perspective, size guides are about protecting both conversion and satisfaction. - **Reduce Size-Related Returns** – Help customers choose correctly before purchasing. - **Increase Purchase Confidence** – Remove hesitation that can stall checkout. - **Improve Customer Satisfaction** – Set clear expectations that align with real-world fit. - **Support Conversion Completion** – Keep users moving forward instead of abandoning due to uncertainty. - **Learn Where Fit Confusion Occurs** – Identify products or categories that need better guidance. When these goals are aligned, size guides become a quiet trust-builder—helping shoppers feel sure about their choice and helping brands avoid preventable friction after the sale. * * * ### **Choose Metrics to Test Your Account Creation** We tested Nike’s size guide as a decision-support experience for shoppers trying to confirm fit before purchasing. A focused design stack of UX metrics was selected by mapping core user needs to observable signals in this moment. The metrics used were Satisfaction, Success, and Comprehension. **Findable → Success**
 In this moment, users are trying to locate sizing information quickly without breaking their shopping flow. Success is an appropriate signal because it shows whether people can identify where to go for sizing details when prompted. This metric captures whether the experience supports forward movement or creates a pause before users even reach the information they need. **Usable → Comprehension**
 Once users reach the size guide, they need to understand what the measurements mean and how the information is structured. Comprehension reflects whether the layout, labels, and measurement logic make sense at a glance. This metric captures whether users can interpret the information without confusion or extra mental effort. **Useful → Satisfaction**
 Beyond understanding, users want to feel that the information actually helps them make a decision. Satisfaction captures the emotional response to whether the size guide feels supportive or merely informational. This signal reflects whether clarity translates into confidence at the moment of choice. * * * ### **Establish Hunches to Direct Your Testing** Starting with hunches helps teams name what feels uncertain before data gets involved. These assumptions shape the questions we ask and help focus the test on moments where confidence or momentum might break down. **Example: Nike Size Guide**

Hunches

Questions

UX Metrics

Shoppers may understand the measurements shown but still feel unsure how to apply them to their own bodies, especially if they don’t know their exact measurements.

How well do you understand what this page is showing?

Comprehension

Users might hesitate if sizing information isn’t clearly surfaced from the product page at the moment they need it.

Click where you would go to find more details about the sizing.

Success

Even with clear data, the size guide may feel more informational than reassuring, limiting how confident users feel about moving forward.

How do you feel about the information on this page provided about this item?

Satisfaction

* * * ### **Turn Hunches into Test Questions** Turning hunches into concrete questions ensures that uncertainty becomes measurable. Pairing each UX metric with a specific question type creates clear signals about where confidence holds and where it breaks. - **Satisfaction (Likert scale)**
 Question type: Likert scale
 Example: How do you feel about the information on this page provided about this item? [Image] - **Success (First-click test)**
 Question type: First-click test
 Example: Click where you would go to find more details about the sizing. [Image] - **Comprehension (Likert scale)**
Question type: Likert scale
 Example: How well do you understand what this page is showing? [Image] * * * ### **Calculate UX Metric Scores from User Feedback** We tested Nike’s size guide as a decision-support experience for shoppers trying to confirm fit before purchasing. In this moment, users were focused on understanding sizing information and deciding whether it gave them enough confidence to move forward. The design stack included Success, Comprehension, and Satisfaction, combining behavioral and attitudinal signals to capture both action and perception. - **Very Good** = 90% and above - **Good** = 70%–89% - **Average** = 50%–69% - **Poor** = 30%–49% - **Very Poor** = below 30% The overall test score was 89% (Good). This score reflects a sizing experience that is clear and dependable for most users, with only minor strain around how confident people feel applying the information to themselves. **Success (93% — Very Good):**
 Most participants immediately knew where to go to find sizing details, indicating that the entry point to the size guide is easy to spot and understand. Users moved through this step without hesitation, showing that access to sizing information does not interrupt shopping momentum. **Comprehension (92% — Very Good):**
 Participants consistently understood what the page was showing and how the measurements were organized. The tables, labels, and structure supported quick interpretation, with little evidence of confusion about what the numbers represented. **Satisfaction (81% — Good):**
 While users generally felt positive about the information provided, responses suggest a slightly more reserved emotional reaction. The page was seen as helpful and clear, but some users still felt they needed to do additional mental work to feel fully confident in their choice. [Image] Taken together, the scores describe a size guide that works well as a clarity tool but only partially as a confidence anchor. The experience minimizes friction and confusion, yet still places responsibility on users to translate measurements into personal certainty. Overall, this is a solid, functional experience that supports decision-making without fully resolving doubt. Click here to check out the [raw survey data and UX metric scores for Nike’s size guide.](https://my.helio.app/report/01KCAH13SMD3AGVMVF9091DQMG) * * * ### **Draw Signals from Your Design Stack** **1\. Focus on poorly scoring metrics** [Image] Nike’s size guide achieved an overall score of 89% (Good), with Success (93%) and Comprehension (92%) performing exceptionally well, while Satisfaction (81%)—though still strong—lagged slightly behind the other metrics. This gap suggests that while users clearly understand how to use the size guide and can successfully complete sizing tasks, the experience doesn’t fully eliminate emotional friction or anxiety around fit. The key signal: the size guide works extremely well functionally, but confidence could be strengthened further at the emotional level. **2\. Use design intuition to identify patterns across metrics** [Image] The pattern shows Nike excels at clarity and task completion. Users understand the sizing logic, trust the measurements, and can quickly find what they need without disrupting their shopping flow. However, slightly lower satisfaction points to lingering doubt—users may still wonder whether the recommendation will actually match real-world fit. This reflects a common tension in size guidance: even when instructions are clear, users want reassurance that the system accounts for body variation, product differences, or prior purchase outcomes. **3\. Determine if user needs are being met** [Image] - Insightful: Exceeded — sizing guidance clearly explains how to choose the right fit. - Usable: Exceeded — layout, labels, and instructions are easy to follow. - Credible: Exceeded — measurements feel accurate and trustworthy. - Efficient: Exceeded — users can access and apply guidance quickly without breaking flow. - Empowering: Met — users feel mostly confident, with minor residual hesitation around real-world fit. **4\. Compare outcomes to your business goals** - Reduce Size-Related Returns: Strongly supported — clear guidance minimizes guesswork. - Increase Purchase Confidence: Achieved — users feel informed before committing. - Improve Customer Satisfaction: Supported — high satisfaction with room to improve emotional reassurance. - Support Conversion Completion: Fully achieved — guidance removes a key checkout blocker. - Learn Where Fit Confusion Occurs: Supported — interaction data can reveal unclear categories or products. **5\. Surface signals & establish a direction** Signals derived from the data: - Users trust Nike’s sizing information and can act on it quickly. - Functional clarity is a major strength, driving high success and comprehension. - Emotional confidence still trails task success, indicating room for reassurance. **Direction based on business context:**
 To further reduce hesitation and strengthen confidence at the decision moment, next steps should include: [Image] - Reinforcing recommendations with contextual reassurance (e.g., “Most customers with similar measurements chose this size”). - Surfacing fit-related feedback or validation signals tied to real purchase outcomes. - Testing lightweight personalization or fit confidence messaging without adding complexity. The signal is clear: ***Nike’s size guide removes confusion and enables confident action—adding emotional reassurance will turn clarity into complete confidence.***