E-commerce
June 30, 2026
"I order from Canada: what US size does your M correspond to?" The agent replies from memory "take an 8". The customer receives a 10. Cross-border return, lost customs duties, one-star review. An approximate conversion costs more than a misrouted ticket.
Zalando points out that the same L or 48 label can cover different measurements depending on the brand, fit, and market (Zalando, sizing 2025). In Europe, up to half of fashion returns are due to sizing.
Shopify recommends adding a US/UK/EU/JP conversion tab to every guide, with a cm/inches toggle (Shopify, sizing guide 2026).
This guide #265 covers customer support for international size conversion. It complements size support (#128) with EU/US/UK, Markets, and cross-border returns.
Summary
Why do international sizes complicate support?
International size conversion support is more than just a generic table found on Google. Each brand calibrated to a main market exports an ambiguity to the others.
Three sources of friction
Different scales: EU numerical, US/UK shifted, JP/KR in cm
Units: customer thinks in inches, size chart in cm
Brand fit: theoretical conversion ≠ product cut
Typical fashion DTC volume
Shops with Shopify Markets: 12 to 28% of sizing tickets mention a foreign country or size. US/UK to EU peak during sales and Christmas. Eightx estimates that 53 to 67% of apparel returns are due to sizing (Eightx, apparel returns 2026).
Example EU denim brand
Brand with 420 tickets/month, 19% US/UK conversion. Agents without brand chart: 11 wrong size cross-border returns / month. Deployment of intl metafields + INTL macros: cross-border sizing returns −34%, intl CSAT 4.5.
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How does it differ from neighboring guides?
Five contents, five scopes.
Size support (#128)
Sizes #128: fit, measurements, bracketing. #265: cross-regional conversion and cross-border returns.
Size guide bot
Size guide bot: PDP automation. #265: agent protocol and INTL-SIZE macros.
Size recommendation bot (#199)
Size recommendation (#199): measurements quiz. #265: customer already mentions a US/UK size and wants the brand equivalent.
International support
International support: language, customs, delivery times. #265: size variant only.
Conversion signals (#260)
Signals #260: tag signal_sizing_intl if Markets country ≠ base catalog.
What data should be structured for SKU conversions?
The international sizing support matrix is based on Shopify metafields, not on Wikipedia.
Recommended Metafields
size_label_primary: EU 38, US 8, UK 12size_chart_json: map region → label per variantfit_note: true to size, runs small/largemeasurements_cm: bust, waist, hip per variantcategory_sizing: tops, denim, footwear, kidsmodel_size_worn: size worn + measurements
Brand Reference Charts (not generic)
Women's EU 38 ≈ US 8 ≈ UK 12 in theory, but your size 38 jeans may measure 72 cm waist vs 74 cm for another brand. Kiwi Size Chart and SmartSize allow international mapping + cm/inches toggle on PDP (Kiwi Sizing, Shopify 2026).
Footwear: foot length in mm
The most reliable cross-border reference. Example: 260 mm = EU 41 = US M 8 = UK 7.5. Always cite the mm length from the product chart.
Sync Markets
Shopify Markets: display local label on PDP (US customer sees US). Support always cites the line of the product chart, not a generic conversion.
What is the 7-step agent protocol for a conversion question?
The agent size conversion protocol avoids memory-based answers.
Identify SKU + variant targeted
Ask for source region: "What size do you wear and in which system (US, UK, EU)?"
Ask for measurements in cm if between two sizes
Open product chart: metafield or category guide
Recommend a brand size + fit note
Quote equivalencies from the official chart only
Remind of the exchange policy cross-border if there is hesitation
Forbidden phrases
"A US 8 is always an EU 38"
"Take the same size as in the United States"
"Google says M = 40"
Approved phrases
"On [product], our chart indicates: EU [X] = US [Y] = UK [Z]. Cut [fit note]. Your measurements in cm would help us refine this. Full guide: [link]."
Which INTL-SIZE-* macros should I use?
Eight international size macros cover 90% of tickets.
INTL-CONV-01 (direct conversion)
"Hello [First Name], for [product], according to our official guide: EU [X] = US [Y] = UK [Z]. Fit: [fit note]. Guide link: [URL]."
INTL-MEASURE-01 (measurement request)
"To guide you accurately, could you please provide your chest, waist, and hip measurements in cm? I will compare them with our [product] table."
INTL-BETWEEN-01 (between two sizes)
"Between [T1] and [T2], we recommend [size] because [fit note / stretch / cut]. Free exchange within [timeframe] if needed."
INTL-US-TO-EU-01
"You wear US [N] for [ref brand]. For [our product], the table suggests [brand size]. Our fits are [slim/loose]."
INTL-UK-TO-EU-01
"UK [N] on our guide = EU [X]. Also check the cm column if you are hesitating between two variants."
INTL-SHOES-MM-01
"Foot length [mm] cm on our shoe guide = EU [X] / US [Y]. Measure in the evening, barefoot, heel against the wall."
INTL-MARKETS-01
"You are viewing the site from [country]. The selector displays [US/EU] sizes. Here is the guide link with unit toggle."
INTL-RETURN-01 (post-purchase wrong size)
"Sorry about the fit. Exchange for [size]: [procedure]. Cross-border return: [fees / timeframe / customs according to policy]."
How do you handle tops, denim, footwear, and kids?
Conversions by category differ: a single table creates errors.
Tops and dresses (women/men)
Prioritize bust/chest + waist in cm. UK women's is often +2 vs US (UK 12 ≈ US 8). Always check the product column, not as a global rule.
Denim and trousers
Cite waist inches + inseam (30x32). EU customer: convert waist cm ÷ 2.54 to compare to US jeans waist. Stretch fit note is critical.
Shoes
US men/women differ (+1.5 women vs men for the same length). UK half-size vs US. Always ask for foot length in mm.
Children
Age ≠ size. Cite height in cm + weight if kids' guide. US 4T ≠ EU 104 without a brand chart. Link to children's support (#263) if age safety question arises.
How to configure Shopify Markets and the chat widget?
The Shopify Markets sizing support aligns with what the customer sees on the PDP.
Markets controls (ops)
PDP displays local label (US store → US sizes)
Size guide translated in FR/EN/DE with region tabs
Cm/inches toggle visible on mobile
Bot/widget detects country IP + market handle
INTL macros translated and validated
Bot intent sizing_intl
Pull size_chart_json + fit_note. Never invent any conversion outside the corpus. Handoff if the reference brand is unknown or if it is vintage without a chart. See Markets bot.
Third-party apps
SmartSize: quiz + mapping in 25 languages. Kiwi: auto-unit by geoloc. Support cites the app result if the customer used it: "Your quiz indicates M, consistent with our chart."
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How to handle cross-border returns for wrong sizes?
The cross-border size return combines logistical friction with EU consumer rights.
EU withdrawal right
14 days after delivery without justification (directive 2011/83/EU). EU customer returning from another Member State: same right. Return shipping costs at their expense unless stated otherwise before purchase (Your Europe, returns).
Outside EU (US, CA, AU, CH)
Store policy prevails. Macro INTL-RETURN-01: deadlines, return fees, non-refundable customs, exchange vs refund. Do not promise customs duty refund if policy excludes it.
International size exchange workflow
Confirm SKU + size received vs desired
Verify stock of target variant for customer market
Create return label or self-service portal
Exchange shipment: specify delivery estimate + tracking
Tag
return_intl_wrong_sizefor fit analysis
Withdrawal button June 2026
Directive 2023/2673: mandatory online withdrawal function from June 2026. Support redirects to the self-service flow, do not process manually if portal is available.
What edge cases and escalations should be anticipated?
Twelve size conversion edge cases to route explicitly.
Between two hybrid systems
Customer mentions S/M/L and wants digital EU sizing: open the product alpha + numeric chart.
Unisex and oversize
Ask for measurements. Do not assume men's/women's fit without a guide.
Vintage / second-hand on site
Vintage US sizes ≠ current sizing. Handoff or "measure flat" if PDP data is available.
Plus sizes and petite sizes
Charts are sometimes incomplete for 3XL+ or XXS. Escalate to merchandising if metafield is empty.
Cross-border gift
FR buyer, US recipient. Macro: recommend based on chart, gift exchange policy, no fit guarantee.
International bracketing
Double US + EU order "to compare": offer INTL-BETWEEN-01 before validation. Double cross-border return cost.
Which KPIs for international sizing support?
Measuring intl sizing KPI support isolates conversion errors from generic fit returns.
Leading KPIs (weekly)
intl_sizing / total sizing tickets
% replies with product guide link: target 100%
Recommendations without measurements: target < 10%
First response time US/UK Markets
Lagging KPIs (monthly)
Return rate wrong size per market
Exchange success rate intl
CSAT tickets tagged intl_sizing
Repeat contact sizing same order
QA
Audit of 15 intl tickets/month: quoted table, fit note, return policy. Feed into quality (#116) and monthly audit (#259).
How does Qstomy help with international sizes?
Qstomy reads metafield tables and the Shopify market to respond with local labels without invented conversions.
Intl sizing features
Intent sizing_intl: pull size_chart_json
Market context: US/EU label on PDP
Quiz sync: Kiwi/SmartSize result if logged in
Macros INTL-* Gorgias sync
Handoff: vintage, between 2 ambiguous systems
Tag signal_sizing_intl for CRO dashboard
Quantified DTC scenario
EU fashion brand + US/UK Markets, 165 intl sizing tickets/month. Before Qstomy: generic bot, 8 wrong size US returns/month, FRT 4 hrs. After metafields + locked bot + INTL macros: wrong size US returns −38%, FRT 52 s bot, intl CSAT 4.6, US Markets conversion +12%, successful exchanges +22%.
Explore AI customer support, Shopify, request a demo.
Which playbooks can be deployed in 2 weeks?
Playbook 1: charts audit (2 d)
Top 30 SKU by market. Check EU/US/UK + cm columns. Fix PDP.
Playbook 2: size_chart_json metafields (1 d)
Fill section 3. Webhook re-index bot. Alert for variant without mapping.
Playbook 3: INTL macros (3 h)
Import 8 macros section 5. EN translation for US shift agents.
Playbook 4: agent training (2 h)
7-step protocol. Quiz on 10 US→EU, UK→EU cases, shoes mm, cross-border gift.
Playbook 5: intl return policy (2 h)
Document section 8. INTL-RETURN-01 macro per market. Test portal.
Playbook 6: monthly review
KPI section 10 + top 5 SKU return_intl_wrong_size. 1 fix fit note minimum. Link to reduce returns.
Useful linking
Converting an international size in customer support is not about doing arithmetic. It means reading the brand's chart, contextualizing the fit, and anticipating the cross-
Enzo
June 30, 2026
