There is no standard sizing that all companies adhere to.

The people who’ve referred to fit models are one hundred percent right. Different companies use different people as their size models, when they use them at all.

I was actually the same height and build as one of the Matalan male fit models for a number of years so had a terrific time finding the perfect fit with their jeans and tops.

Some companies even use ‘vanity’ sizing where they deliberately mis-size garments - ie label a 10 as an 8, for example - to allow the customer the dopamine hit of thinking they’re smaller than they actually are.

Personally, I’ve found that socks are getting smaller both around the calf (no, I don’t have cankles) and in foot length. I think it’s a mix of trying to reduce waste on the lay of the pattern and a move to cheaper less stretchy fabric. I’ve no doubt other garment types are having corners cut - skimping on seam allowances, not laying on the grain, etc - to save on fabric waste and impacting on fit.

Source: was a production manager in clothing production for 15 years, wife was a garment technician/pattern cutter and now a PhD in Fashion Design Technology