Best Shopify Size Chart Apps for Hat and Cap Stores
By TWIWT Team Last updated
Kiwi, ESC Size Charts, SmartSize, and MP Size Chart are four Shopify apps worth shortlisting when an online hat or cap store needs to display and manage sizing tables. Shortlist Kiwi for catalog-wide assignment rules, ESC for straightforward chart publishing, SmartSize for flexible modular editing and previews, or MP for a centralized size-guide directory.
Choose based on how your headwear catalog is structured, how shoppers access the chart on product pages, and how your team maintains supplier updates. Camera-based head measurement and personalized size recommendations are separate capabilities, detailed below.
Product information checked on September 15, 2026. Published by TWIWT, the maker of TWIWT Head Measurement. This guide compares documented capabilities; we have not conducted a hands-on performance benchmark. “Best for” recommendations reflect the specific operational workflows described below.
Shopify size chart apps compared
The table summarizes vendor-documented features. Mobile support claims indicate responsive design options, but store owners should still verify how each chart renders within their specific Shopify theme.
| App | Product assignment | Popup display | Measurement units | Mobile | Maintenance |
|---|---|---|---|---|---|
| Kiwi Size Chart & Recommender | Products, collections, vendors, types, tags, and metafields; matching conditions and priorities | Supported | Automatic unit conversion and location-based unit detection | Responsive charts listed | CSV imports, reusable layout rules, and chart priorities |
| ESC Size Charts | Products, collections, tags, vendors, and product types | Popup or on-page charts | Automatic conversion not confirmed in the listing reviewed | Responsive charts listed | Templates; import/export available on Premium |
| Smart Size Chart & Size Guide | Products, collections, types, and tags; ANY/ALL conditions and priorities | Supported | Automatic unit conversion | Mobile layout options and in-editor preview | Modular editor, bulk import/export |
| MP Size Chart & Size Guide | Individual products; collection/tag rules and advanced assignment depend on plan | Supported | Automatic unit conversion | Responsive display listed | CSV imports and an automatically synchronized size-guide directory page |
Assignment details verified via Kiwi documentation, SmartSize editor reference, and MP documentation.
1. Kiwi: best for detailed chart-matching rules
Shortlist Kiwi when different headwear brands, manufacturers, or product categories require different sizing charts.
Its matching conditions combine catalog attributes. For example, a merchant can assign a chart only when a product belongs to a specific vendor and has a designated product type. Priority settings resolve overlapping assignments when a general cap collection contains items with differing sizing standards (such as fitted caps versus unstructured strapbacks). See Kiwi product matching.
Kiwi also documents popup modals, responsive layouts, automated unit conversions with location detection, and CSV imports.
Plan consideration: The Shopify listing currently allows three published charts on Free, ten on Premium at $7.99/month, twenty on Plus at $14.99/month, and unlimited charts on Ultimate at $26.99/month. Plus and Ultimate carry additional order-volume charges. See Kiwi plans.
Check before choosing: Assign two overlapping rules to a sample product and verify that the intended chart takes priority. Granular matching rules require consistent catalog tagging and ongoing team hygiene.
2. ESC Size Charts: best for a straightforward chart workflow
Shortlist ESC when your main requirement is publishing reusable size guides with minimal operational overhead.
ESC documents popup and on-page presentation, Shopify 2.0 theme app blocks, and assignment by product, collection, tag, vendor, or product type. Its free plan includes three published charts; Premium offers unlimited charts and import/export capabilities for $4.99/month. Both tiers list mobile responsiveness. See ESC features and pricing.
Check before choosing: Automatic centimetre-to-inch conversion was not confirmed in the listing reviewed. If a dynamic unit switcher is essential, confirm that capability before committing. Alternatively, assess whether dual-unit columns (displaying cm and inches side-by-side in approved tables) satisfy your shoppers’ needs.
3. SmartSize: best for flexible chart editing and previews
Shortlist SmartSize when your team needs to build, customize, and revise guides containing tables, measurement diagrams, and supporting instructions.
Its modular editor documents draft and active states, configurable content blocks, granular display rules, and desktop/mobile previews. These controls allow a merchandiser to inspect a chart’s formatting before making it visible on the storefront. See SmartSize editor reference.
SmartSize also lists bulk import/export, automatic unit conversion, and image-to-chart generation. Its free plan includes two charts without a watermark; Starter offers ten charts at $9/month, while Growth provides unlimited charts at $12/month. See SmartSize features and plans.
Check before choosing: Build one complete hat chart during evaluation. Verify that circumference ranges (e.g., 56–57 cm), fractional sizing labels (e.g., 7 1/8), and measurement instructions render cleanly across screen sizes. Check every value generated from an image against the supplier’s source specification.
4. MP Size Chart: best for a central size-guide page
Shortlist MP when you want product-level chart popups alongside a dedicated central page collecting your store’s sizing guides.
MP documents an automatically synchronized size-guide directory page that reflects chart updates, CSV imports, automatic unit conversion, and customizable popup styling. Its documentation also details assignment by product, collection, or tag. See MP product listing and MP documentation.
Plan consideration: Starter is free and includes three published charts with individual product assignment. Growth adds rule-based assignment and ten charts at $6.95/month; Pro lists unlimited published charts at $12.95/month. See MP plans.
Check before choosing: Verify that your required rule-assignment logic is supported on your chosen tier. Organize the central directory by recognizable brand or product family so customers can easily locate the relevant table.
What should hat and cap stores evaluate?
Headwear sizing involves unique challenges: cranial dimensions, rigid crowns, and fractional sizes leave little margin for error. We recommend evaluating these apps against your actual catalog using the following criteria.
Product assignment: does the correct chart appear?
Test your assignment rules against five representative headwear archetypes:
- A fitted cap with numeric size labels: verifying fractional increments (e.g., 7, 7 1/8, 7 1/4).
- A hat using alpha sizing: verifying S, M, L, and XL boundaries.
- An adjustable cap: displaying continuous circumference spans (e.g., 55–60 cm).
- A multi-brand catalog: confirming that Brand A’s size table does not overwrite Brand B’s differing measurements.
- Accessory exceptions: ensuring that non-headwear items (e.g., beanies, hat bands, cleaning brushes) do not inherit a fitted cap table simply because they share a collection.
Popup placement: can shoppers reference it without friction?
Confirm that the size-guide trigger button sits directly beside the size selector or variant dropdown on product pages. Open the popup, review the chart, and close it on both desktop and mobile devices.
The popup should clearly state the brand or product family. Measurement instructions must explicitly illustrate where to place a measuring tape: around the largest part of the head, approximately 1 cm above the ears and across the mid-forehead.
Units: separate measurement conversion from size labels
Converting centimeters to inches does not determine a fitted-cap size.
Unit conversion merely alters the measurement notation (e.g., 58 cm to 22 7/8 inches). Mapping that measurement to a numeric hat size (7 1/4) or an alpha label (Large) requires the manufacturer’s specific grading chart.
Preserve the supplier’s original sizing boundaries and check that automatic conversion rounding does not obscure the boundary between adjacent sizes.
Mobile display: check your actual tables
Open the chart on a mobile phone within your store’s live or staging theme:
- Can shoppers read column headers and numbers without zooming?
- If horizontal scrolling is required, is the visual affordance obvious?
- Are the unit switcher and modal close button easy to tap with one thumb?
- Do measurement diagrams and text remain readable alongside the table?
Treat vendor mobile-responsiveness claims as a starting point to verify against your specific theme.
Maintenance: rehearse a supplier update
Have the team member responsible for sizing updates complete a dry run:
- Update one measurement range.
- Confirm the change propagates across all assigned product pages.
- Add a new headwear SKU to the catalog and verify automatic rule assignment.
- Confirm that unrelated product lines remain unaffected.
Keep a dated record of supplier source charts. A centralized sizing tool is only effective while its data and rule assignments remain accurate.
Size recommendations are a separate capability
A size chart displays available sizes and physical dimensions. A size recommender applies logic or customer input to suggest a specific size. A measurement tool captures the customer’s physical dimensions.
Some tools combine aspects of these functions, but merchants should evaluate each capability independently.
| Tool | Documented recommendation capability | What a headwear merchant should establish |
|---|---|---|
| Kiwi | Custom inputs and conditional recommendation logic | Whether a configured circumference input maps correctly to each product’s sizing boundaries |
| SmartSize | Fit quizzes and size recommendations on Pro tiers | Whether the supported inputs and questionnaire logic suit headwear dimensions rather than general apparel |
| MP Size Chart | Algorithmic size recommendations listed | Whether the tool supports cranial circumference and specific hat size labels |
| ESC Size Charts | Personalized recommendations not confirmed in reviewed listing | Whether displaying static size charts is sufficient for your store |
| TWIWT Head Measurement | Camera-based head measurement widget; matches captured dimensions to merchant product charts | How the Shopify app handles your catalog’s specific charts, assignments, and size boundaries |
Sources: Kiwi custom recommender, SmartSize plans, MP listing, ESC listing, and TWIWT product overview.
Where does TWIWT Head Measurement fit?
Consider TWIWT Head Measurement when shoppers hesitate or abandon purchases because they do not know their head circumference.
TWIWT Head Measurement is an embedded widget that measures head circumference using the shopper’s device camera in a desktop, tablet, or mobile browser—without requiring a physical tape measure. The tool then matches that measurement against your product’s specific size chart to recommend the appropriate size.
Its Shopify listing supports measurements in centimeters and inches, custom sizing charts, and a free tier of 50 requests per month.
Where it fits your store: TWIWT Head Measurement is not a general table-management app; its role is solving the missing-input problem on your product pages. When customers hesitate or order multiple sizes (bracketing) because they don’t know their head size, camera measurement gives them the clarity to choose. However, if your immediate goal is simply publishing and organizing static size tables across a large multi-brand catalog, start with the dedicated chart apps above.
For a broader analysis of these workflows, read Size Chart vs Size Recommender: What Headwear Stores Need.
Frequently asked questions
Which Shopify size chart app should a multi-brand hat store shortlist first?
Start with Kiwi if catalog-level matching conditions (combining vendor, tags, and product types) are your main requirement. SmartSize is an alternative when modular layout editing and preview workflows matter most. Test both with representative products from your catalog to determine which update workflow your team can maintain accurately.
Can multiple hats share one size chart?
Yes, as long as they share identical sizing specifications and manufacturer grading. Group them through the app’s supported assignment rules. When a manufacturer uses unique circumference ranges or grading intervals, create a distinct chart to prevent customer confusion.
Does an adjustable cap need a size guide?
Yes. While adjustable caps accommodate a wider span of head sizes, shoppers still need to know the minimum and maximum circumference range (e.g., 54–61 cm) and the closure mechanism (snapback, strapback, buckle). An adjustable label should clarify fit boundaries, not replace them.
Does a general automated size recommender support hats and caps out of the box?
Do not assume that it does. Most sizing tools are engineered for apparel dimensions (chest, waist, hips, height, weight) rather than cranial circumferences. Verify which specific inputs the tool requires, how it maps circumference measurements to hat sizes, and how it handles shoppers whose measurements fall directly on size boundaries.
What should an online store do when shoppers do not know their head measurement?
Provide clear manual measurement instructions illustrating tape placement. If shoppers frequently hesitate, ask customer support sizing questions, or engage in bracketing (ordering two sizes to return one), evaluate an embedded camera measurement tool such as TWIWT Head Measurement to provide an instant measurement directly on the product page.
Can a store use a dedicated size chart app and TWIWT Head Measurement together?
Yes. A store can use a chart app such as Kiwi or ESC to publish comprehensive size tables and measurement instructions, while embedding TWIWT Head Measurement on fitted headwear pages to help shoppers obtain their measurement and receive a direct size recommendation.
Choose for the task your store needs to complete
For catalog chart management, prioritize reliable product matching, clear mobile presentation, and efficient maintenance. Add recommendation logic when shoppers need help interpreting complex grading charts. Consider camera-based measurement when shoppers struggle to take their own measurements.
For a direct comparison of sizing workflows, read TWIWT Head Measurement vs Kiwi Sizing.