SmartSize is a Shopify size recommendation app that covers every sizing category in one install: men, women, boys, girls, dogs, and cats. One “Find My Size” button opens the right fit quiz for each product, so shoppers in every category get a personal size recommendation.
Most size finder apps on Shopify only cover adult clothing. Men’s shirts and women’s dresses get a fit quiz. Kids’ jackets, dog harnesses, and cat sweaters only get a static size chart.
This is a real problem. 48% of online returns are size-related, and not only in adult fashion. Parents return kids’ clothing at even higher rates because children grow fast. Pet apparel returns are also high, because a “medium” dog coat can fit one breed and not another.
SmartSize solves this with one app. Each product page shows one “Find My Size” button. The button opens the quiz for that product’s category, with the measurements that matter for that body type. You do not need extra apps or manual workarounds.
In this guide:
- Women’s fit quiz — AI-powered size recommendations
- Men’s fit quiz — casual wear to tailored suits
- Kids’ fit quiz — boys and girls
- Pet sizing quiz — dogs and cats
- Why one app for every category?
- How to set up fit quizzes on Shopify
- FAQ
Women’s fit quiz — AI-powered size recommendations
The women’s fit quiz is SmartSize’s most advanced size assistant. It offers two modes.
Prediction Quiz (AI-powered): The shopper enters height and weight. Then she answers four visual body shape questions: weight distribution, waistline shape, belly shape, and optional bra size. A machine learning model predicts her body measurements and matches them to the product’s size chart. No tape measure is needed. The quiz takes about 30 seconds.
Precision Quiz: The shopper enters real body measurements, such as bust, underbust, waist, and hips. This mode is best for shoppers who already know their measurements or want exact matching.
Both modes end with SmartSize’s interactive fit visualization. It shows a body silhouette for each size, color-coded fit bars per measurement, and a size explorer carousel to compare every option.
For women’s clothing, available measurements include: bust, underbust, waist, hips, shoulder, arm length, inseam, neck, height, and weight. Merchants choose which measurements matter for their products.
SmartSize works for dresses, activewear, lingerie, and swimwear. It acts as your store’s virtual fitting room, without cameras, extra apps, or AR technology. Shoppers see how each size fits their body. This builds confidence and reduces size-related returns.
→ Try the women’s fit quiz on our demo store
Men’s fit quiz — casual wear to tailored suits
The men’s fit finder uses the same two quiz modes, with body shape questions adjusted for male proportions.
Prediction Quiz (AI-powered): The shopper enters height and weight, plus three visual questions: shoulder and torso width, belly shape, and buttocks shape. The AI model predicts chest, waist, hip, and other measurements from these inputs.
Precision Quiz: The shopper enters chest, waist, hips, inseam, neck, arm length, and height directly.
SmartSize also has a garment fit setting. This is a key difference from a basic size chart app. Merchants tell the algorithm how their clothing is designed to fit:
| Fit type | Best for |
|---|---|
| Regular fit | T-shirts, jeans, casual wear |
| Structured / fitted | Blazers, dress shirts, tailored suits |
| Body-hugging / slim | Compression wear, performance gear |
| Relaxed / flowy | Hoodies, oversized tees |
A slim-fit dress shirt and a relaxed hoodie should not produce the same recommendation, even for the same shopper. SmartSize’s AI sizing engine adjusts the matching algorithm for each quiz based on this setting.
The fit visualization shows men where a size is tight or loose: chest, waist, and hips. They can compare other sizes and choose with confidence. This is the difference between a real size recommendation app and a simple lookup table.
→ Try the men’s fit quiz on our demo store
Kids’ fit quiz — accurate sizing for boys and girls
Kids grow fast. A size finder for children’s clothing must handle bodies that change month to month. It must also handle sizing differences between brands, which make parents unsure about every purchase.
SmartSize offers separate quiz categories for boys and girls. Each uses the Precision Quiz with age-appropriate measurements:
- Girls’ clothing: bust/chest, waist, hips, inseam, neck, arm length, height
- Boys’ clothing: chest, waist, hips, inseam, neck, arm length, height
Parents enter their child’s measurements and get a personalized size recommendation based on the product’s specific size chart. The mannequin viewer and fit bars show where each size fits. Parents get the same clarity that adults get from the AI prediction quiz.
Why kids’ sizing needs a dedicated fit quiz
- Brand inconsistency — a “size 6” is different at every brand
- Growth spurts — parents need to see whether the next size up still fits or is too large
- Gift purchases — relatives who buy for kids they have not seen in months need reliable guidance
- Between-sizes problem — kids often fall between sizes; SmartSize shows which size fits better and why
A kids’ size chart app that only shows a static table does not solve the between-sizes problem. SmartSize’s visual fit breakdown lets parents compare sizes and make an informed choice. This reduces returns and increases trust in your store.
→ See the kids’ fit quiz in action
Pet sizing quiz — dogs and cats
Pet apparel is one of the fastest-growing e-commerce categories. It is also one of the hardest to size correctly. A Labrador and a French Bulldog are both “large” dogs, but their body proportions are completely different. Static size charts fail here more than anywhere else.
SmartSize includes dedicated fit quizzes for dogs and cats, with measurements designed for animal bodies:
| Measurement | Dogs 🐕 | Cats 🐈 |
|---|---|---|
| Neck circumference | ✅ | ✅ |
| Chest / girth | ✅ | ✅ |
| Back length | ✅ | ✅ |
| Weight | ✅ | ✅ |
Pet owners enter their animal’s measurements and get a personalized size recommendation. They see the same visual fit breakdown, with fit bars that show how each measurement maps to each available size.
Why pet stores need a size recommendation app
- No standardized sizing — pet clothing sizes differ a lot between brands
- Breed diversity — a “medium” sweater fits some breeds but not others
- High return rates — pet apparel returns often exceed 40% due to sizing
- Measurement confusion — pet owners do not know which measurements matter; SmartSize guides them with illustrated instructions
Do you sell dog coats, cat harnesses, pet costumes, or breed-specific apparel on Shopify? SmartSize is the only size assistant that treats pet sizing with the same depth as human sizing: dedicated measurements, visual fit visualization, and per-product matching.
→ Try the pet sizing quiz on our demo store
Why does your Shopify store need one size finder for every category?
One size finder for all categories gives shoppers a consistent experience, costs less, and keeps your analytics in one place. Merchants who sell across categories often use a mix of tools: one app for women’s sizing, a different widget for men’s, a static page for kids, and nothing for pets. This creates three problems:
1. Inconsistent shopper experience. Women’s customers get an AI-powered fit quiz. Kids’ customers get a PDF. Pet customers get a basic FAQ about measuring their dog. The experience should be the same everywhere.
2. Multiple subscriptions and integrations. Each sizing app has its own billing, its own setup, and its own theme integration. More apps means more complexity, more cost, and more things that can break.
3. No unified analytics. You cannot compare sizing performance across categories if each one uses a different tool. SmartSize gives you a single dashboard with quiz usage, recommendation accuracy, and coverage across all product types.
SmartSize covers every category in one install
| Category | Quiz type | AI model | Key measurements |
|---|---|---|---|
| Women’s clothing | Prediction + Precision | ✅ Yes | Bust, underbust, waist, hips, inseam, arm, neck |
| Men’s clothing | Prediction + Precision | ✅ Yes | Chest, waist, hips, inseam, arm, neck |
| Girls’ clothing | Precision | — | Bust/chest, waist, hips, inseam, arm, neck |
| Boys’ clothing | Precision | — | Chest, waist, hips, inseam, arm, neck |
| Lingerie | Precision | — | Bust, underbust, waist, hips |
| Dogs 🐕 | Precision | — | Neck, chest, back length, weight |
| Cats 🐈 | Precision | — | Neck, chest, back length, weight |
One Shopify app. One subscription. One theme integration. Every product category gets a dedicated fit quiz designed for that body type.
SmartSize works as a virtual fitting room alternative, without cameras, AR technology, or body scanning. Shoppers tap “Find My Size”, answer a short quiz, and see how each size fits in an interactive view.
Try SmartSize for freeHow do you set up category-specific fit quizzes on Shopify?
Setup takes four steps: create a quiz per category, link each quiz to products, add one app block to your theme, and customize the look. It takes minutes, not days.
Step 1: Create quizzes per category
For each product category (for example women’s dresses, men’s suits, kids’ jackets, or dog coats), create a quiz:
- Select the category (man, woman, boy, girl, dog, cat)
- Upload or enter the size chart — or let AI size chart extraction read it from an image
- Choose the quiz type (Prediction, Precision, or both)
- Configure which measurements to collect
Step 2: Link quizzes to products
A single quiz can cover many products. Link by:
- Collection — “Women’s Dresses” collection → women’s quiz
- Product type — all “Dog Coats” → dog sizing quiz
- Vendor — all “Nike” products → Nike-specific quiz
- Tags — “kids-winter-2026” → kids’ quiz
Step 3: Add SmartSize to your theme
Add one app block in the Shopify theme editor. All quizzes, across all categories, run through the same widget. The correct quiz loads automatically based on the product the shopper is viewing.
Step 4: Customize
Set your accent color, button text, icon style, and default units. These settings apply to all categories, so your brand stays consistent. You can override them per quiz where needed.
The “Find My Size” button automatically shows the right quiz for each product. A shopper browsing dog coats sees the pet quiz. A shopper browsing men’s shirts sees the men’s quiz. No manual routing is needed.
Frequently asked questions
What is a fit finder app for Shopify?
A fit finder app (also called a size finder, size assistant, or size recommendation app) helps online shoppers find the right size before they buy. Instead of reading a static size chart, shoppers take a short quiz and receive a personal size recommendation based on their body measurements. SmartSize is a fit finder that covers men’s, women’s, kids’, and pet clothing in one app.
Does SmartSize work as a virtual fitting room?
SmartSize works as a virtual fitting room alternative. Shoppers see how each size fits their body in an interactive visualization with a body silhouette and color-coded fit bars. Unlike camera-based virtual fitting rooms, SmartSize needs no app download, no photos, and no AR technology. It is faster, simpler, and works on every device.
Can I use SmartSize for kids’ clothing on Shopify?
Yes. SmartSize includes dedicated fit quizzes for boys and girls with age-appropriate measurements: chest, waist, hips, inseam, arm length, and height. Parents enter their child’s measurements and get a visual size recommendation that shows how each size fits.
Is there a Shopify size recommendation app for pet clothing?
SmartSize is one of the only Shopify size recommendation apps with dedicated pet sizing. It includes fit quizzes for dogs (neck, chest, back length, weight) and cats (neck, chest, back length, weight). Pet owners get the same interactive fit visualization as human clothing shoppers.
What’s the difference between a size chart app and a fit finder?
A size chart app displays a static table of sizes and measurements. A fit finder (or size recommendation app) goes further: it collects the shopper’s body data and recommends the best-fitting size. SmartSize does both. It shows a personalized size chart and gives an AI-powered fit recommendation.
Does SmartSize support men’s tailored clothing?
Yes. SmartSize offers configurable garment fit settings: regular, structured/fitted, body-hugging, and relaxed. For tailored men’s clothing such as suits, blazers, and dress shirts, the structured fit mode only recommends a size if every measurement falls within that size’s range.
How does the AI prediction quiz work?
The AI prediction quiz uses a machine learning model to estimate body measurements from height, weight, and visual body shape questions. It is available for men’s and women’s clothing. It takes about 30 seconds and needs no tape measure. The predicted measurements are matched against the product’s specific size chart to produce a personal recommendation.
Can one Shopify store use SmartSize for multiple categories?
Yes. This is what SmartSize is built for. A single store can run quizzes for men’s, women’s, boys’, girls’, and pet clothing at the same time. Each quiz is linked to the relevant products, and the correct quiz loads automatically on each product page. One app, one subscription, every category.
What languages does SmartSize support?
SmartSize supports 26 languages with automatic detection. The quiz displays in the language your customer selected in your store. Supported languages include English, Spanish, French, German, Italian, Portuguese, Japanese, Korean, Chinese, Arabic, and more.
How much does SmartSize cost?
SmartSize starts at $0 with a Free plan that includes 2 size charts. Paid plans range from $9/month (Starter) up to $499/month (Pro 10K, with 10,000 monthly size recommendations). The size quiz is unlocked at the Pro tier ($19/month, 100 recommendations). Annual billing saves 20% — Pro 100 drops to $15.20/month effective ($182.40/year). Every paid plan includes a 14-day free trial and no overage charges. See full pricing →
Give every shopper — and every pet — the right size
Size-related returns happen in every category: women’s fashion, men’s suits, kids’ winter coats, and dog sweaters. SmartSize solves the sizing problem across all of them, with one app, one integration, and one consistent experience.
Your store’s size finder should work for every product you sell, not only adult clothing.
SmartSize is Built for Shopify — Shopify’s top-tier quality badge, awarded to apps that meet the highest bar on storefront performance, admin integration, and merchant experience. You can install it straight from the Shopify App Store. No theme code and no developer needed.
Want the full deep dive? Read our complete SmartSize guide. It covers every feature, integration option, and customization in detail.
Questions? Reach out at [email protected].
— Philip, co-founder of SmartSize
