Overview: Reducing uncertainty in online fashion sizing

Shopping for clothes online should feel effortless, yet sizing uncertainty remains the biggest barrier. Poor fit is a major driver of apparel returns, which costs brands money and erodes customer trust. At Lumeve, we set out to solve this problem.

Lumeve is a digital sizing assistant that gives shoppers confidence in choosing the right size, reduces return rates, and helps brands strengthen their relationships with customers. This case study highlights the end-to-end process: from research and insights to wireframes and prototypes. Each design decision focuses on addressing the root challenge of sizing accuracy, not just surface-level fixes, with the goal of creating a shopping experience that is both reliable and rewarding.

Lumeve UX Case Study Preview

  • Project Type: Solo project, guided by instructor feedback

  • Duration: 12 weeks, April to July 2025

  • Role: UX/UI Designer (end-to-end process)

  • Platform: Web & Mobile

  • Focus: Sizing, inclusivity, trust

  • Tools: Figma, Miro, Canva, FigJam, Photoshop, HTML/CSS

Discovery

What’s The Problem?

Why Online Sizing Fails

Online apparel sizing is a costly problem. Fit uncertainty drives returns, which costs retailers money and weakens customer trust.

For shoppers, every brand feels different. The result is hesitation at checkout: “Should I order a small or a medium?” “Will this brand run tight?” This uncertainty frustrates shoppers, discourages them from exploring new brands, and drives unnecessary returns.

In interviews, participants called returns exhausting and frustrating, and they often avoided unfamiliar brands entirely because of sizing risk. This human cost sits behind the metrics. It is the reason Lumeve focuses on confidence at the moment of choice.

“I avoid new brands entirely, returns are just too much of a headache.” Interview participant

Assumptions & Hypotheses

Before conducting research, I captured the assumptions I held about online sizing challenges. These assumptions shaped the hypotheses that guided my design and testing.

Assumptions

  • 1-Shoppers primarily abandon carts because of uncertainty about size.
  • 2-Brand size charts are confusing, inconsistent, and often ignored.
  • 3-Fit guidance tools are generic, not personalized, and fail to build trust.
  • 4-Returns are accepted as “part of online shopping,” even though they are costly and frustrating.

Hypotheses

  • 1-H1: If sizing guidance is personalized and visible at the decision point, shoppers will feel more confident at checkout.
  • 2-H2: If size recommendations are explained transparently (“why this size”), shoppers will be more likely to trust the guidance.
  • 3-H3: If brand comparisons are provided, shoppers will try new retailers rather than sticking only to familiar brands.

How Might We

How Might We help shoppers feel confident choosing a size at the moment of checkout, so they can try new brands without hesitation and retailers see fewer size-related returns?

Final result: clear, inclusive sizing guidance that builds shopper trust and reduces returns.

Research Findings

These findings shaped three priorities: a lightweight Fit Profile, clear brand to brand comparisons, and transparent size recommendations that appear at the decision point.

Every participant reported inconsistent sizing

Every participant in our interviews mentioned size inconsistency across brands. This creates uncertainty, discourages trying new retailers, and fuels returns.

All

Shoppers hesitate to buy from new brands

Without reliable sizing information, shoppers avoid exploring unfamiliar brands, limiting discovery and reducing growth opportunities for retailers.

Sizing doubts lead to abandoned carts

Shoppers leave items unpurchased when unsure if a size will fit. This hesitation translates into lost sales and frustration.

Design

“I love the convenience of online shopping, but inconsistent sizing makes it a gamble. I want to try new brands with confidence.”

User Persona: Nazanin Vahab

Bio

Nazanin is a 26-year-old university student in Vancouver who shops online for convenience and variety. She loves browsing fashion on her phone during study breaks, but uncertainty around fit makes the experience stressful. She values her time and budget, and wants guidance she can trust so she can explore new brands without the hassle of returns.

Goals

  • Feel confident choosing the right size the first time
  • Shop quickly and comfortably on mobile
  • Reduce the risk and hassle of returns
  • Explore new brands and styles without worry

Frustrations

  • Sizing varies unpredictably across brands
  • Size charts are generic and unreliable
  • Returns waste time and money
  • Constant doubt between two sizes at checkout

Behaviors

  • Relies on reviews to judge fit
  • Sometimes orders two sizes and returns one
  • Shops mainly on mobile while multitasking
  • Avoids unfamiliar brands due to risk
  • Feels anxious when she cannot trust the size info

Empathy Map

Desire for certainty and ease

  • “Does this brand even fit me?”
  • “Should I order a small or a medium?”
  • “I hope I picked the right size.”
  • “At least I can return it if it doesn’t work.”
  • Scrolls Instagram and brand sites for fashion ideas
  • Reads reviews and compares size charts
  • Checks return policies before adding to cart
  • Double-checks details before checkout
  • Orders two sizes when unsure, then returns one
  • Excited at first, but cautious
  • Frustrated by inconsistent sizing
  • Anxious about wasting time and money
  • Relieved when something fits well
  • Disappointed when items need to be returned
  • “Sizing is unpredictable across brands.”
  • “Returns take too much time and energy.”
  • “I want to feel confident at checkout without guessing.”

Effortless Path to the Right Fit

The flow mirrors real shopping behavior to build confidence at every step. From a light Fit Profile to clear size recommendations on the product page, each moment is designed to reduce hesitation and increase trust.

Key stages: Onboarding → Create Fit Profile → PDP size guidance → Brand comparison → Confident checkout.

Solution Overview

I designed Lumeve, a sizing assistant that reduces hesitation and returns by making fit guidance clear, personal, and visible at the exact moment of choice. It combines a quick Fit Profile, brand comparisons, and inline recommendations shown at the size picker.

The Fit Profile is intentionally short, three questions, because the research pointed to hesitation rather than desire as the real blocker: shoppers described abandoning carts over sizing doubts, so a longer intake would have added exactly the friction we were trying to remove.

  • 👤
    Fit Profile: three quick steps tuned to the shopper.
  • 📍
    Inline Guidance: a size callout placed at the picker.
  • ✔️
    Why This Size: one short reason that builds trust.
  • 🔄
    Brand Comparison: familiar fits across labels.

Outcome: a guided path from Fit Profile to checkout that increases confidence and reduces size-related returns.

  • Welcome screen
  • Create account screen
  • Log in screen
  • HomePage
  • Details
  • Favourite

Wireframe Preview

High level wireframe preview
View Figma
Expanded wireframe view

Validation

Lumeve User Testing

Two remote rounds with five participants focused on clarity, guidance, and confidence at size selection. Round one exposed navigation gaps and unclear labels. Round two confirmed that reflowing the Fit Profile, clarifying onboarding, fixing dropdown placement, and scaling icons improved task completion and confidence.

Round One

Search clarity, homepage guidance, required labels

Before Round One, screens before changes
After Round One, screens after changes

Key findings

  • Users overlooked the search bar, the placeholder felt vague.
  • Homepage lacked a clear starting point.
  • Required field indicators and gender labels were unclear.
  • Participants wanted default size formats and quick measurement help.

What changed

  • Added a visible search label and clearer placeholder.
  • Introduced a “Start with your size profile” entry point.
  • Made required status explicit and clarified gender labels.
  • Standardized units and default size formats.

Outcome: Search became discoverable and the Fit Profile entry point was clearer, improving first time navigation.

Design System

Typography and Voice

Blending Heritage with Modern Elegance

Lumeve’s design system blends typography and color to create a voice that is both modern and timeless. EB Garamond brings elegance and heritage, and IBM Plex Sans adds clarity and accessibility. The brand voice is elegant and intentional, quietly confident and culturally rooted, so the interface feels warm, clear, and credible.

EB Garamond sample

EB Garamond

Regular, Medium, SemiBold, Bold

IBM Plex Sans sample

IBM Plex Sans

Regular, Medium, SemiBold, Bold

Color Palette and Emotion

Charcoal#2C2C2C
Off White#F9F8F6
Saffron Gold#F2B134
Saffron 400#F7D085
Isfahan Blue#165C7D
Isfahan 400#6F9AAE
Isfahan 100#DCE7EC
Qajar Red#B0332A
Sage Mist#AEB7AD
Gray#E0E0E0

Bringing It All Together

Final Designs

A quick look at key screens

Autoplay running, press Pause to scroll

  • Screen 1
  • Screen 3
  • Screen 4
  • Screen 6
  • Screen 7
  • Screen 8
  • Screen 11
  • Screen 12
  • Screen 13
  • Screen 15
  • Screen 16
  • Screen 17
Opens in Figma, mobile friendly

The experience

Four steps from doubt to the right size

  1. Build your Fit Profile

    Answer a few quick questions about height, weight, preferred fit, and familiar brands. Lumeve turns the answers into a simple profile that powers every later recommendation.

    Why: Keeps intake short, so the profile never becomes the friction it is meant to remove.

    Lumeve app screen, profile
  2. Get smart recommendations

    Tailored size suggestions appear on every product page, each paired with a clear “Why this size” explanation.

    Why: Showing the reasoning is what makes a suggestion believable.

    Lumeve app screen, recommendations
  3. Compare brand sizing

    See how sizing differs across brands like Zara, H&M or Uniqlo, so a new label feels less of a gamble.

    Why: Cross-brand references target the hesitation to try unfamiliar brands.

    Lumeve app screen, brand comparison
  4. Shop with confidence, save favorites

    With a Fit Profile in place, checkout feels effortless. Favorite brands and fits are saved for quick reuse.

    Why: Saved fits turn a one-time setup into a faster next visit.

    Lumeve app screen, favorites

Designing the Marketing Site With User Voices

The Lumeve marketing website was shaped directly by user insights, not just product features. Research revealed four key audience groups: Fit Seekers, Self-Expression Explorers, Data-Driven Decision Makers, and Inclusivity Advocates. These groups guided the headlines, imagery, and interactions, ensuring the site built trust and spoke to real shopper needs.

Watch Prototyping
Laptop mockup of the Lumeve marketing page

Multi-Platform Accessibility

A seamless fit experience, on every device

Lumeve adapts across mobile, tablet, and desktop so shoppers can feel confident wherever they browse. Core flows, selecting gender, adding body details, and viewing recommendations, remain intuitive and responsive. Accessible layouts, clear labels, and inclusive design ensure that every user feels supported throughout their sizing journey.

Outcome

Two rounds of testing made the Fit Profile usable.

Five participants across two remote rounds. Whether Lumeve reduces size-related returns would need a retail pilot.

  • Round 1 findingThe search bar was overlooked and the homepage lacked a starting point.

    ChangeVisible search label, a "Start with your size profile" entry point, explicit required fields and standard units.

    Tested
  • Round 2 findingFit Profile inputs were crowded and units inconsistent; filters and icons were hard to place.

    ChangeFit Profile reflowed into steps, units normalised, filters relocated, icons scaled.

    Tested
  • Round 2 findingLogin mixed social and form sign-in without separation.

    ChangeSocial sign-in separated from the form with clear labels.

    Tested
  • HypothesisA transparent "Why this size" explanation increases trust in the recommendation.

    Design responseExplanation beside each recommendation, plus cross-brand comparison.

    Untested

Still open: a retail pilot measuring size-related returns, size switches and first-time brand conversion; until then, confidence ratings and time to size choice are the realistic proxies. An accessibility audit of the size picker is also pending.