Shoe Size Chart for Shopify Stores: US, UK and EU Conversion (and Why It’s Never Exact)

Short answer: US, UK and EU shoe sizes use different step sizes, so conversions are always approximate. The most reliable anchor is foot length in cm or inches. Show foot length as the first column, add US, UK and EU sizes from your own lasts, and label the conversions approximate.

Why shoe size conversions are never exact

EU (Paris point) steps are 6.67 mm; UK and US steps are 8.47 mm

ISO 19407:2023 (footwear sizing conversion systems) aligns major systems to foot length. From the standard’s freely available preview text:

• The European (Paris point) system uses a grading interval of 6.67 mm, starting at zero.
• The UK system uses 8.47 mm, starting at 101.6 mm (4 inches).
• The US system uses 8.47 mm, starting at 99.5 mm.

Different step sizes and different starting points mean whole-size labels rarely line up one-to-one.

Different starting points, and last length vs foot length

Sizing systems grew up around last length or foot length depending on country and era. ISO 19407 treats foot length as the common reference for conversion tables. Shoppers still see labels based on how each brand marks the shoe, so two “EU 42” shoes can fit differently.

What ISO 19407:2023 says

The standard provides conversion tables for Mondopoint, European and UK systems, plus China, Japan, Korea and the US, based on foot length. It notes that systems developed differently over many years, and that Tables 1 and 2 are a guideline for consumers, not a perfect mapping. It also states it does not cover overall fit properties such as width, volume, or toe depth.

ISO’s technical tables can disagree with market labelling. The preview notes, for example, that the technical conversion may show UK 8 ≡ EUR 41.5 while footwear is often labelled UK 8 / EUR 42. Prefer your brand’s measured chart over a copied internet grid.

Start with foot length: how shoppers should measure their feet

1. Stand on a sheet of paper with your heel against a wall.
2. Mark the tip of your longest toe.
3. Measure heel to toe in cm or inches.
4. Repeat for the other foot and use the longer measurement.

Measuring later in the day is a common tip (feet can swell slightly). Treat that as a tip, not a standard. Put these steps next to your chart so shoppers do not guess.

Sample shoe size chart (adults)

Example only. Approximate conversions. Replace every number with your supplier’s or brand’s lasts before you publish.

This extends the short shoe table on the templates hub. Keep the hub’s summary and send merchants here for the full explanation.

These rows follow a common brand-chart pattern. ISO 19407 Table 2 puts a 250 mm foot at EUR 39.5, UK 6.5, US men 7.5 and US women 8.5, about half to one size different. That gap is why you should publish your brand’s own numbers.

Men’s vs women’s US sizes

ISO 19407:2023 describes the US scale as the UK scale plus one size for men and usually two sizes for women, so its tables put women’s US about one size above men’s for the same foot length. Brand charts vary, so check each brand’s own chart. For multi-gender catalogues, publish separate charts or clear columns per gender from each brand.

Kids’ shoe sizes

Kids’ scales are separate. In the UK and US systems described by ISO 19407, the first 13 sizes are children’s sizes, then the scale restarts at 1 for larger sizes. Show foot length first, add an age band only as a rough guide, and label age as approximate. Do not mix adult and kids rows in one table without a clear heading.

Width, volume and fit notes

ISO 19407 conversion tables are about length. They do not solve width or volume. If a style runs narrow, say so next to the chart (“runs narrow”, “true to size”, “wide fit available”).

Practical pattern for Shopify:

• Keep the length table clean (foot length + size labels).
• Put width in a short note under the table, or as a separate column only when you grade width (for example B / D / EE) with real stock.
• Mention volume (high instep, chunky sneaker last) in product-level fit notes when returns show a pattern.

Fit-note language for shoppers is a separate topic for a later post. Until then, keep notes short and specific to the product.

How to show this in Shopify

1. Build a text table in the grid editor, or start from the Shoes template (it comes with US, EU and Foot length columns in cm; add a UK column). Image charts work but are harder to read on phones.
2. Set Primary unit to Centimeters or Inches. Type column names without units: the app adds the unit to measurement columns, for example Foot length (cm). Tick No unit on label for size columns like US, UK and EU. If you change the unit later, the app asks whether to convert the numbers (rounded to the nearest 0.5, which is coarse for foot length, so check them) or keep them. A chart uses one unit, so to show both, add a second column named, for example, Foot length, inches, tick No unit on label, and type the inch values yourself. Do not write (in) in brackets at the end of a column name, because the app removes it.
3. Assign the chart by collection (for example Sneakers) or by vendor for multi-brand stores. Assignment by product, collection, tag, or vendor has no plan gate; Free limits you to 3 published charts. Deep dive: different charts per product.
4. Add the theme app block on your product template (popup/modal or inline). Full install steps: how to add Honest Size Charts and how to add a size chart in Shopify.
5. Test on a phone. Wide conversion tables often need fewer columns or sideways scroll. See size charts on mobile.

Free plan: 3 published charts, no watermark. Pro: $8.99/month or $89/year for unlimited charts. No separate trial.

Dropshippers and multi-brand stores

If you sell several brands, do not publish one global US/UK/EU table for every shoe. Brands grade differently. Create one chart per brand (or per brand + category), assign by vendor, and replace the sample numbers with that brand’s size guide. When a supplier only gives EU sizes, still show foot length if you can measure a sample; otherwise label the conversion approximate and link to your return policy.

Baymard (Jul 2022) notes that international conversions and both cm and inches help shoppers who know their size in another system. One test user in that research used a site’s chart to check a US shoe size. The lesson for merchants: put the conversion where the size selector is, not three clicks away.

FAQ

See the FAQ block below for quotable answers on why conversions are approximate, how to measure feet, men’s vs women’s US sizes, and width notes.

Build one shoe chart per brand and assign it by vendor or collection. Install on Shopify.

Next: Templates hub · Size chart vs size guide · Pricing