Size converters

Sizes vary by region and by brand. The converters here are calibrated against the most common retail conversion charts; for an exact fit always cross-check the manufacturer’s own size guide.

Shoe sizes are where regional drift hurts the most: US, UK, EU, Japan, and the Mondopoint millimeter system all anchor on slightly different reference lasts, so a “US 10” from a running brand and a “US 10” from a dress-shoe maker can differ by a full size in interior length. The converter here uses the most common industry chart but exposes the underlying foot length in millimeters (Mondopoint), so you can compare brand size charts apples-to-apples even when the labelled US/UK numbers disagree. Bra sizing follows the modern band-rounding method, not the legacy +4 / +5 formula — measure under-bust, round to the nearest even number, and the cup letter follows from the bust-band difference. Ring sizes are anchored on inner diameter in millimeters, which is the only measurement that travels reliably between US, UK, EU, and JP conventions. For all three categories, measuring at the end of the day (when feet and fingers are slightly swollen) gives the most forgiving fit.