Does a European 38 mean the same on shoes and clothes?

No, and it is the most common mix-up there is. EU 38 in a women's shoe is a US 7.5; EU 38 in a women's top is a US M. The two ladders are unrelated.

Why do reviews say a brand runs small when the chart says otherwise?

Usually because reviewers compare the label against the size they normally wear at home rather than against the brand's own measurements. If the label is in another system, everybody reports the same offset and it reads as "runs small".

Is Japanese sizing really one step smaller?

In letters, effectively yes: a US men's M converts to a Japanese L. Japanese shoe sizes are not "smaller" at all — they are the foot length in centimetres, which is exact.

Should I always size up when buying online?

No — that just moves the returns from too-small to too-big. Convert the label first, then check the garment's centimetres against something you own that fits.

What "runs small" really means

Half the time a brand does not run small at all. It is telling you the truth in a system you are not reading in.

"Size up, it runs small" is the most repeated advice in online shopping, and it hides two completely different problems. One is real: a brand whose pattern is genuinely cut narrow. The other is an accounting error — the label is in a system that is not yours, and nothing about the garment is unusual at all.

The second is worth ruling out first, because it takes ten seconds and it is free.

Tell-tale signs the label is not in your system

A number in the 30s or 40s on a top or a dress. That is the European ladder: a EU 40 dress is a US 8, and a UK 12.
A shoe number in the 20s. Japan prints the foot length in centimetres: 24.5 is a women's US 8.
A shoe number in the hundreds. Korea, same length in millimetres — 245.
Two numbers with a slash. Chinese labels give height and chest in centimetres: a men's 175/92 is height then chest, and it is a US M.
A letter that is one step off. Japanese letter sizes run a step smaller than US ones — a US men's M is a Japanese L. That single step is behind an enormous share of "this brand runs small" reviews.

The same number means different things on different garments

A "38" is not a size. It is a number that four systems all use for something else. On a European women's shoe, 38 is a US 7.5. On a European women's top, the same 38 is a US M. Same digits, unrelated meanings — which is why "what is a 38?" has no answer until you say what it is on.

Women's — Shoes
USUnited States	EUEurope	UKUnited Kingdom	JPJapan	KRKorea	CNChina
5	35	2.5	21.5	215	35
5.5	35.5	3	22	220	35.5
6	36	3.5	22.5	225	36
6.5	37	4	23	230	37
7	37.5	4.5	23.5	235	37.5
7.5	38	5	24	240	38
8	38.5	5.5	24.5	245	38.5
8.5	39	6	25	250	39
9	40	6.5	25.5	255	40
9.5	40.5	7	26	260	40.5
10	41	7.5	26.5	265	41
11	42	8.5	27.5	275	42

When a brand genuinely does run small

Some do. Fast fashion tends to be cut for a slimmer fit model and graded tightly; Japanese and Korean brands are cut for a different average body, and a European-labelled garment made for a European market is not the same block as the American version of the same brand. None of that shows up in a conversion table, because it is not about the system — it is about the pattern.

There is only one reliable test, and it is the same one every time: find the garment's measurements in centimetres and compare them to a garment you already own that fits. Chest across, waist across, and the length. A brand's own product page usually gives them. Two numbers settle an argument that a thousand reviews cannot.

Keep the answer once you have it

The awkward part is that this knowledge is per-brand and it evaporates. You work out that you are one size at this label and another at that one, and six months later you are standing in a queue with no idea which was which. Writing it down — which brand, which category, which size actually fit — turns a research task into a lookup, permanently.

Common questions

Does a European 38 mean the same on shoes and clothes?: No, and it is the most common mix-up there is. EU 38 in a women's shoe is a US 7.5; EU 38 in a women's top is a US M. The two ladders are unrelated.
Why do reviews say a brand runs small when the chart says otherwise?: Usually because reviewers compare the label against the size they normally wear at home rather than against the brand's own measurements. If the label is in another system, everybody reports the same offset and it reads as "runs small".
Is Japanese sizing really one step smaller?: In letters, effectively yes: a US men's M converts to a Japanese L. Japanese shoe sizes are not "smaller" at all — they are the foot length in centimetres, which is exact.
Should I always size up when buying online?: No — that just moves the returns from too-small to too-big. Convert the label first, then check the garment's centimetres against something you own that fits.

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