Rendered Fits · Merchant guide
Size recommendation app for Shopify fashion brands
Rendered Fits is a Shopify app that recommends a size for the exact product a shopper is viewing, worked out from the merchant’s own size chart, fit notes and garment measurements. It also sizes whole outfits with Complete the Look and adds virtual try-on previews. The Free plan covers one product; Complete is $349 per month with a 14-day trial.
By the Rendered Fits team · Reviewed 1 October 2026
A size advisor for the product the shopper is buying
Rendered Fits combines AI size recommendation, virtual try-on and Complete the Look outfit building in a Shopify app. For a luxury or premium fashion catalogue, the practical question is whether a suggestion makes sense for the particular garment, its cut and the shopper's measurements.
The current Shopify listing, checked 1 October 2026, describes a reusable fit profile, recommendations matched to each product’s size chart, sized outfits, optional photo try-on and analytics. Review these features on your own products; the listing is not evidence of a guaranteed accuracy or returns result for your store.
A generated image answers a visual question. It does not establish that a waistband, sleeve or shoulder will fit. Use the sizing versus virtual try-on guide to decide which questions your shopper journey needs to answer.
Size chart, size recommender or virtual try-on?
| Tool | Shopper question | What to prepare |
|---|---|---|
| Size chart | What are the measurements for each size? | Accurate tables, units and clear body-versus-garment labels. |
| Size recommendation | Which available size is suggested for me? | Shopper inputs and product-specific sizing information. |
| Virtual try-on | How might this item look on me? | A suitable shopper photo and clear product imagery. |
Prepare size information that deserves trust
- Identify the measurement type. Body measurements and finished-garment measurements are different. Label them clearly. A garment can include wearing ease beyond the body measurement.
- Keep units consistent. State centimetres or inches for each table. Do not mix half-width measurements with full circumferences.
- Match tables to the actual product. A jacket and a fitted top should not inherit a generic chart merely because both use S, M and L.
- Check every offered variant. Compare size labels, availability and supplied information, including any gaps or unusually large jumps between sizes.
- Review boundary cases. Test someone between sizes, an unavailable size and missing sizing information. Make uncertainty visible instead of forcing a confident answer.
Use the downloadable size-chart checklist to organise this review. Most stores have room to improve: in our audit of 829 Shopify fashion stores, only 31.6% had a size chart readable as text and only 20.3% of sized products said how they fit. Check yours with the free size chart audit.
Body size is only one part of garment fit
A body-measurement chart tells shoppers which body dimensions a size is intended for. A finished-garment chart describes the item itself. Label the two clearly: a size advisor cannot safely interpret them as interchangeable.
Fit and ease need context. A relaxed wool coat may allow room for a layer underneath, while a close-fitting top has a different intended silhouette. Stretch, lining, construction and the shopper's preferred fit can change how a dimension should be interpreted. Record those product details and check how a provider uses them; do not assume that every listed input is supported automatically.
International size labels also need product-level checking. Treat UK, US and EU conversions as labels mapped to your actual variants and charts, rather than proof that two brands' garments share a fit. Our clothing size converter shows the usual label mappings.
Check the categories that make your catalogue distinctive
Use this table to choose sample garments for a sizing pilot. These are evaluation prompts for your team, not a promise of automatic support for every material or construction.
| Category | Fit information to inspect | Useful review case |
|---|---|---|
| Tailored jackets and coats | Chest, shoulder, sleeve and length; intended layering and lining. | Chest falls in one size while shoulders or sleeves need another. |
| Dresses and occasionwear | Bust, waist, hip and length; fitted areas, closures and fabric stretch. | Shopper spans sizes across bust and hip. |
| Trousers and denim | Waist, hip, rise and inseam; cut and stretch. | Correct waist size but an unsuitable length or rise. |
| Knitwear and relaxed silhouettes | Measurement method, intended volume and material behaviour. | A shopper prefers a closer fit than the product's intended shape. |
| Co-ords and separates | Individual charts and available variants for each piece. | Shopper needs different sizes for the top and bottom. |
Pair these checks with the luxury fit evaluation worksheet. For image fidelity and brand presentation, read our luxury fashion virtual try-on guide.
What to ask when choosing a garment-size advisor
- Which evidence drives the suggestion? Ask whether the tool uses a body chart, garment dimensions, shopper inputs or order outcomes, and what happens when those inputs disagree.
- How are recommendations tied to products? Test two garments with the same S–L labels but different cuts. Check the actual suggested variant, including sold-out and missing sizes.
- How is uncertainty handled? Review incomplete charts, between-size measurements and conflicting dimensions. An unsuitable confident answer should fail your review.
- Does the experience suit your brand? Check mobile completion, chart visibility, wording and the path from recommendation to basket. Keep size guidance distinguishable from the visual preview.
- What evidence supports the result? Ask for the denominator, product mix and method behind accuracy or returns claims. Compare with your own pilot instead of adopting a vendor headline as your forecast.
A worked example: why product details matter
Consider a shopper with a 92 cm chest and a jacket listed with a 100 cm chest measurement. The 8 cm difference is not automatically a sizing error: it may be the garment’s intended ease. Conversely, a chart that lists a 92 cm body measurement means something different. This example is illustrative and is not a Rendered Fits recommendation rule. Confirm the chart’s meaning before interpreting the suggested size.
Evaluate sizing on your store
Start with a small selection of products where your team knows the fit well. Check recommendations against product information and real fit feedback. Record when recommendations cannot be evaluated, rather than counting unknowns as correct.
Measure recommendation use separately from purchases, and measure size-related returns only after the return window has matured. Buying a recommended size is adoption; it does not by itself prove accuracy. Our measurement guide defines these stages. Compare sizing and photo-preview workflows in the Shopify app comparison.
Rendered Fits has an ongoing Free plan and optional paid-plan trials for eligible merchants. See current plans, limits and billing terms.
Questions merchants ask
Which Shopify app recommends a clothing size from my size chart?
Rendered Fits recommends an available product size using a shopper fit profile and your product size chart, fit notes and garment information. Keep body measurements distinct from finished-garment measurements, and test the recommendations on supported adult products before a wider rollout.
Can shoppers get a size recommendation without uploading a photo?
Yes. Shoppers can use personalised sizing without uploading a photo. They complete a reusable fit profile, then receive a recommendation for a supported product using the available sizing information. Photo-based virtual try-on is an optional appearance preview, separate from the size decision.
What happens if a product has no usable size chart?
A usable product chart provides evidence for a recommendation. Where a general estimate is available without one, it must be identified as an estimate; some products remain unsupported. Keep your size chart accessible, label its units and measurement type, and check missing data before launch.
See whether Rendered Fits suits your store
Try your product imagery, check size guidance and review the shopper journey before rolling out.
Plan a measurable sizing trial
Use the Shopify conversion evaluation guide to define eligible shoppers, purchases and mature returns. Our size-chart statistics explain why published chart information is a separate check from recommendation accuracy.