Designer Sizing, Decoded: What Italian 42, French 36½, and Armani 44 Actually Mean
There's a moment that stops a lot of good purchases: you find the piece, you look at the size, and it says 42.
Forty-two what? A calculator will give you a number. The problem is that the number is wrong about as often as it's right — and when the piece exists only once, in one size, with no second chance, "about as often as it's right" isn't good enough.
Here's what's actually going on.
The conversion charts disagree with each other
This isn't a matter of finding the correct chart. There isn't one.
One widely used guide converts an Italian 42 to a US 6. Another puts a European 42 at a US 10, then adds that an Italian 42 tends to land closer to a US 6 to 8. A third argues that Italian sizing runs smaller than the broader European system entirely, and that an Italian 44 corresponds to roughly a German 38 or a French 40.
All three are describing the same tag. They can't all be right, which means none of them can be trusted on their own.
Why the same number fits differently
Three things move independently of the number on the label.
Country of origin. Italian, French, and German houses use overlapping numbers on different scales. The tag says 42 in all three cases. The garment is not the same garment.
The cut. Italian tailoring is generally drafted closer to the body and tapered through the waist, where American ready-to-wear is drafted with more ease. Two size-42 skirts, identical on paper, will sit differently at the hip because they were patterned for different silhouettes.
The house. Within Italian sizing, a Chanel 42 and a Max Mara 42 are not interchangeable. Chanel's tweed pieces tend to run narrow through the shoulder and armhole. Max Mara's outerwear is cut with room to layer, because that's what a coat is for. Same number, different garments, different bodies.
What to do instead
Measure a piece you already own and love. Not your body — a garment. Lay it flat and measure the waist across, the bust across, the length from the shoulder seam. That's your reference, and it's more useful than any size you've ever been told you are.
Read the fabric. A wool-cashmere blend with some give forgives an inch. A structured silk or a fitted tweed jacket does not. The same margin of error is fine in one and fatal in the other.
Look at the photos for construction, not just color. Where the waist sits, how the shoulder is cut, whether a jacket is meant to close or hang open. A double-breasted blazer with a defined waist has less tolerance than a straight, boxy one.
Size up if you're between. A tailor can take a waist in for very little. Nobody can add fabric that isn't there.
Vintage sizing is a different problem entirely
The charts above assume a garment made in the last decade or so. Push back further and the ground shifts again.
Sizing has drifted steadily larger over the past fifty years — the same measurements that were labeled one number in 1985 carry a smaller number today. It's gradual, it's unofficial, and no house documents it. Which means a vintage piece labeled a 10 may correspond to something closer to a modern 6, and a vintage 42 may not behave like a current 42 at all.
There's no formula for this. There's only the garment. When you're looking at something older, the tag is a historical artifact rather than a measurement, and everything depends on the piece in front of you.
Shoes have their own logic
Clothing sizing is inconsistent. Shoe sizing is inconsistent and unforgiving, because a jacket that's slightly generous through the shoulder is still wearable and a shoe that's slightly narrow is not.
The rough conversion for women's footwear is to subtract about 30 from the European size — a 38 lands near a US 8, a 39 near a US 9. But half sizes complicate it immediately, and Italian shoes in particular tend to be cut narrow through the toe box regardless of length. A 36½ from one house and a 36½ from another can differ by a full half size in practice.
Two things worth knowing: the shape of the shoe matters as much as the number. A pointed toe eats length that a round toe doesn't, so the same foot may need a half size up in one and not the other. And heel height changes fit — a higher heel pushes the foot forward and makes the toe box effectively smaller. A pump and a flat from the same maker, in the same size, will not feel the same.
None of this is a system you have to learn. It's a set of reasons to stop treating the tag as the final word.
The number tells you where a piece came from and roughly what era it belongs to. It doesn't tell you whether it will fit you. That comes down to the house, the cut, the fabric, and the specific garment — and once you know to look at those instead of the number, most of the guesswork goes away.