To be utterly confused by sizing!

[Alittlenonsensenowandthen]

Not sure if this is really an aibu but ...

I wear a size 12 in clothes.jist recently bought a fat face dress in a 12 and fits lovely. None of my clothes are tight. If anything my jeans are a little loose but I'm slightly too flabby to wear a 10. So ...I go to order a ski outfit and thought I'd measure myself to get a good fit on their stuff. It says I'm a size 14-16 in the top and 16-18 on the bottom.
I'm 5"5', 10st and looking a bit porkier than usual and I hold all my weight around my middle but seriously, this much difference in size?! I'm worried now that I'm kidding myself on how big I am! Never bothered measuring before, just went on clothes sizes 🤦
In answer to my misery I cracked open the camembert and wine...

Sports wear & outdoor pursuits wear tend to be less vanity sizing. It’s just a number, are you usually 3 sizes up from the smallest size, look at it that way. And you can cut the size label out once you’ve got the perfect fit.

I guess the question is, that if vanity sizing is so generous do I need to rethink?! I've always said that if I got bigger than a 12, I'd diet back down. Should I be thinking an 8?!

I think I am the same size as you you, comfortable in a 12 BUT I am much bigger than I was 20yrs ago, and 20yrs ago I was also a 12......so, the size 12 of 20yrs ago must have been about a size 6-8 in todays sizing. I deny this to myself all the time though.

It's easy to deny, I'm a size 12 and I'm slimmer then most people around me everywhere I go so I think I'm okay, but then see things about how size 12 today is a 16 in old terms..
Can't imagine how tiny people were.

Same here. I was a 14 for a while in my teens but look back at photos and was way way thinner than now but buy a 14 today. I reckon I'd have been an 18 in older times as I'm small and round.

It’s the distribution of weight and change of shape as you get older too. In my youth, I weighed about 7 stone up to 7.10 and was a size 8-10. I have a few size 8 things now, but mostly 10, but the weight is difficult to keep off the mid section, which is why clothes don’t fit the same. Size 10 today, must have been size 14-16 then.

Forget sizing, it's meaningless. Many European brands, especially Italian, are much smaller than UK sizing.

Consider honestly whether you are 'flabby' especially around the middle, that's most important for health, your waist should be half your height or less.

For a point of comparison with the Olden Days. In the 70's, I wore UK size 14, I was 5'7" and 9 stone 4 pounds and had a quite well proportioned figure on my tallish frame: 36 bust, 25 waist, 38 hips. I don't recognize UK sizing now. (I also don't recognize my figure now, but that's another matter!)