Treat conversion charts as a starting point
Sizing varies by brand, pattern block, last and collection. A Japanese size label, European shoe size or US garment size does not map perfectly to every other system. Use the maker's current chart for the exact product and market.
Measure the garment or foot
For clothing, compare chest, shoulder, waist, hip, rise and inseam with a garment that fits. For shoes, measure both feet while standing and use the maker's guidance for width and last. Record measurements in centimetres and check whether the listing gives body or garment dimensions.
Account for intended fit and fabric
Tailoring, ease, stretch, lining and layering change the correct size. A loose silk blouse, structured jacket and knit polo can fit very differently even from one label. Ask how the model fits and whether the fabric shrinks or relaxes.
Protect cross-border purchases
Before ordering, confirm local return shipping, refund currency, duties and whether alteration makes a return impossible. Save the size chart at the time of purchase, since brand charts and product specifications can change.