Why Italian Sizes Run Small
The most common avoidable loss in cross-border wholesale is not a bad price. It is a size run that arrives correct on paper and wrong on the rail, because two systems were treated as one.
Italian menswear numbers a jacket 46, 48, 50, 52 and so on, rising in steps of two. Those numbers are not the same as the German or French numbers that look identical. As a rough working rule an Italian 48 sits where a German 46 sits, one step below what the same figure means further north. Womenswear runs 38, 40, 42, 44 on a similar offset.

Cut compounds the arithmetic. A great deal of Italian ready-to-wear is drafted closer through the chest and shorter in the body than its northern equivalent, so even a correctly converted size can read as one size down to a customer who has never worn the label.
The consequence lands in your size curve, not in your spreadsheet. A pack built on a northern curve, heavy in the middle, will strand its small sizes and sell out of its large ones. You end up marking down the exact pieces you bought most of.

The fix is dull and it works. Buy one sample of the middle size, measure it flat, and compare the measurements against a garment you already sell well. Chest, shoulder, sleeve, body length. Four numbers settle in ten minutes what a conversion chart argues about forever.
Then shift the curve rather than the labels. If the cut runs one size small for your customer, buy one step up across the run instead of relabelling anything. Relabelled sizes come back as returns and take the customer with them.
Publish the measurements where your customer can see them. Shops that show a flat measurement table alongside the size take fewer returns than shops that show a conversion chart, because a number in centimetres does not need translating.