Hello Bruce,

Thank you for reaching out.

At the moment, EasyStore does not have a built-in size-system switcher that allows customers to toggle between EU, UK, and US sizes while keeping the inventory tied to a single base size.

As an alternative, most merchants implement this by keeping one primary size system for the variants (for example EU sizes) and providing a size conversion chart on the product page to help customers choose the correct size. This avoids the need to duplicate variants while still giving customers clear size guidance.

If you require automatic size switching between different systems, it would typically require a custom solution.

Hope this helps. Let us know if you have any other questions.

Thanks.