Glossary
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size-guide
E-commerce sizing guide: definition of sizing charts, cm fit measurements, vs Shopify variants, reduction of friction returns, and fashion advice.
Updated on
June 4, 2026
A size guide (size guide, sizing chart) is a resource on an online store that helps the customer choose the right size before purchasing: XS to XXL chart, measurements in centimeters, fit (slim, regular), US/UK/EU equivalences, or recommendation according to body shape. Essential in fashion, sports, or footwear, it reduces returns, purchase friction, and customer service queries related to product variants.
Summary
Size guide definition
The size guide answers the question: which size variant should I order for my body or my use? It complements photos, description, and the variant selector on the product page.
Common formats are to be read as practical references to fully understand the topic.
Correspondence table: columns for size (S, M, L) and measurements (chest circumference, hips, sleeve length in cm); Guide by category: "How to choose your size" page for dresses, jeans, shoes; Fit finder / quiz: a few questions (usual size, body shape) followed by a recommendation; Model info: "The model is 1.78 m tall and wears a size M" on the product page; Guide by brand: Nike vs Adidas vs house brand, as measurement charts differ.
Useful distinctions are to be read as practical references to fully understand the topic.
Size guide vs variant selector: the selector allows you to choose S/M/L; the guide explains which choice to make; Size guide vs Product FAQ: the FAQ answers specific questions; the guide outlines the reference measurements; Size guide vs fit (cut): the fit describes the volume (slim, oversized); the guide indicates which size to take for that cut; Global store guide vs product-specific guide: some items have an atypical fit (runs small/large); Static guide (PDF, image) vs dynamic guide (app, Shopify metafields depending on SKU).
Why size guides are important in e-commerce
Without a clear guide, the customer hesitates, orders two sizes "just in case," or gives up. In online ready-to-wear, size uncertainty is one of the leading causes of returns and customer service contact.
Reduce returns: fewer size exchanges, lower logistics costs (product return); Increase conversion: confidence to click "Add to cart" (conversion); Limit abandonment: size doubt = pre-purchase friction (cart abandonment); Unburden support: fewer tickets like "what size for 1.70 m?" (customer support); Strengthen credibility: transparent brand, reviews mentioning "fits well" (customer reviews); Optimize CRO: testing guide placement, "slim fit" wording (CRO); Cross-border: EU/US/UK equivalences prevent errors on international B2C.
A well-designed size guide is a profitable lever: low production cost, direct impact on net margin after returns.
Expected content in a size guide
Elements to include in an effective size guide:
Measurements in cm (and inches if US clientele): chest, waist, hips, inseam; How to measure: "take your chest measurement flat, without pulling tight"; Fit indication: "this model runs small, take one size up"; Visual diagram: silhouette with measurement arrows; Comparison: "if you wear an M at [brand X], take an S here"; Returns / exchanges: policy reminder if the size does not fit.
Use case: a DTC jeans brand displays a "Size Guide" link on each product page that opens a table: size 32 = waist circumference 84 cm, straight fit. The description specifies "runs true to size, refer to the guide". Customer reviews tag "true to size" or "take +1". After a few months, returns due to "incorrect size" drop significantly and the add-to-cart rate on mobile increases. The team enhances the product FAQ with two generic questions linking back to the guide.
For shoes or accessories (belts, rings), adapt the units (EU/UK shoe size, circumference in mm).
Setting up a size guide on Shopify
Shopify does not provide a comprehensive native size guide, but offers several approaches (Shopify Help Center):
Dedicated Page: Online Store > "Size Guide" Pages, linked from the footer menu or product page; Product Metafields: "sizing_chart" field (HTML or image) displayed in the theme via Liquid; Custom Theme Block: "Size & Fit" accordion under the Add to Cart button; Sizing Apps: Kiwi Sizing, Smart Size Guide, Fit Quiz recommend a size based on measurements; Shopify Variants: "Size" option on each product; the guide documents the mapping of measurements → option; Theme 2.0: reusable "Size chart" section assigned by collection (dresses, pants).
Typical merchant workflow:
The process is understood as follows: Measure production samples (flat measurements); Create table by collection or by SKU if fit varies; Publish via page or metafield; link from product page template; Test on mobile (table readability, horizontal scroll); Update after recurring feedback or change of supplier.
An AI chat like Qstomy can supplement the guide by answering "I am 1.65 m, 62 kg, what size?" based on the published grid.
Points of vigilance to be aware of
To keep this topic useful for the store, it must. above all, be linked to a concrete goal: better informing the customer, making operations more reliable, or improving conversion. Visible without excessive scrolling: "Size guide" link above or next to the variant selector Mobile-first: responsive tables, not just an unreadable PDF on smartphones Honesty about the fit: "runs small/large" prevents disappointment and returns Clear units: cm by default in France, toggle cm/inches if needed Photos on model + measurements reinforce the guide Sync with stock: do not recommend a size that is out of stock (inventory management)
The main points to watch out for concern data consistency, readability for the buyer, and the team's ability to maintain the system over time. Analyzing returns: "too small/large" reasons feed guide updates Generic guide copied from an Asian supplier (inconsistent grids) Guide hidden in the footer with no link on the product page Blurry image table or untranslated on a multilingual store Forgetting shoes / accessories in a mixed store Never updating after a pattern change (pattern)
In summary
In summary, size guide = help in choosing a size variant via measurements and correspondences. Formats: cm table, fit, quiz, model info, brand equivalences. Challenges: fewer returns, higher conversion, less friction and customer service. Shopify: page, metafields, theme block, sizing apps. Visible placement, mobile, honest fit, continuous updates.
Associated terms, FAQ, and going further
Associated terms
Product variant: size = variant option.
Product FAQ: Q&A size details.
Purchase friction: size doubt = obstacle.
Customer reviews: field feedback on the fit.
Product return: consequence of choosing the wrong size.
FAQ
Is a size guide mandatory in e-commerce?
Not legally mandatory, but highly recommended as soon as you sell sized items (clothing, shoes). Without a guide, returns and abandonment increase.
Where should the guide be placed on the product page?
Ideally near the size selector: text link, ribbon icon, or "Size and fit" accordion. Avoid hiding it solely in the footer.
Size guide and Shopify variants: how to link?
Create the Size option (S, M, L, 38, 40...) on the product. The guide documents which option to choose according to measurements; sizing apps can pre-select the variant.
How to reduce size returns?
Combine an accurate guide, fit photos, reviews, an easy exchange policy, and return analysis. See return rate reduction strategies.
Go further
Sources: Shopify Help Center (Product variants), Shopify Help Center (Metafields).
Enzo
June 4, 2026
