Rias Gremory’s official US shoe size does not appear to be canonically stated in the sources I found, so there isn’t a verified answer to give. A fan-reference page notes her height and body measurements, but not a US shoe size, and retail listings only show generic or product-specific sizing rather than her character’s exact size.

What’s available

  • The most reliable character reference I found lists her height as 172 cm and body measurements, but no shoe size.
  • One anime merchandise listing uses a shoe-size field for the product, not for Rias herself.
  • A cosplay product page says shoe size should match the wearer’s foot length, which also doesn’t establish a character canon size.

Practical take

If you’re asking for cosplay or fan art accuracy, the safest answer is: unknown / not officially specified. For a fan estimate, people sometimes infer a size from height and proportions, but that would be speculation rather than a confirmed fact.

TL;DR: There’s no confirmed official US shoe size for Rias Gremory in the sources I found.