Alright, let’s talk about something that’s been on my mind, and probably on yours if you’ve ever tried to buy their clothes: Theory clothing sizing. For the longest time, it felt like a complete mystery to me, a real roll of the dice every time I wanted to get something.

I’ve always liked Theory’s style, you know? That clean, minimalist look. Good quality stuff, usually. But what’s the point if you can’t figure out what size to get? I remember a few times I ordered something online, so excited, and then it arrived, and it was either comically large or I could barely get it on. So frustrating!
So, I decided I needed to figure this out, at least for myself. It wasn’t like I launched a full-scale investigation or anything, but I started paying way more attention. My first step was to go through my own closet. I pulled out all the Theory pieces I’d accumulated over the years – some hits, some definite misses in terms of fit.
My Little Sizing Experiment
I laid them all out. Looked at the tags. A size 6 in pants from a few years ago fit completely differently from a size 6 in a newer pair. What gives? Then I started making a mental note, or sometimes an actual note, of how different items fit. Were the pants generally tighter? Were the tops looser?
Then came the “field research” phase. Whenever I found myself in a department store or a Theory shop, I made it a point to try things on. Even stuff I wasn’t planning to buy. I’d grab a blouse in my usual size, and then one size up. I’d try different styles of pants – the wide-leg ones, the slim-fit ones. It was all about gathering data, really.
Here’s what I kind of pieced together from my efforts:

- Pants can be tricky. For me, especially their more tailored trousers, like the ones made from that nice wool. I often found I needed to go up a size from what I might wear in, say, a more casual brand. If there’s not a lot of stretch in the fabric, definitely be careful.
- Tops and blouses seemed a bit more forgiving. Sometimes, my usual size felt right, or even a little generous. Maybe it’s because the styles are often a bit drapey or designed for a looser fit.
- Sweaters were all over the place. Some of their knitwear is intentionally oversized, so your normal size works fine or you could even size down if you don’t want it too baggy. But then, the more fitted sweaters? Yeah, I often felt like I needed to size up again.
- Dresses really depend on the cut. A structured sheath dress? That’s going to be fitted, and you need to be precise. Something more A-line or flowy offers more leeway.
- Don’t forget about the fabric! This became a big one for me. If something has stretch, like elastane or spandex in the mix, it’s generally more forgiving. If it’s a rigid fabric like 100% linen or some structured cottons, I’m much more cautious.
So, What’s My Strategy Now?
After all this, do I have a foolproof system? Not exactly. Sizing is still a bit of a beast. But I definitely feel more confident navigating it now.
My number one rule is: if you can, try it on. Nothing beats actually feeling the garment on your body. Seriously, it saves so much guesswork and potential return hassles.
If I absolutely have to buy online, I’ve learned to be a bit of a detective. I scrutinize the fabric composition. I look at how it’s described – “slim fit,” “relaxed fit,” “true to size.” Though, “true to size” can mean different things to different brands, can’t it?
I also started paying more attention to the specific collection or line within Theory, if there is one. Sometimes different lines have slightly different fit profiles. It’s subtle, but it can make a difference.
It’s still not perfect, and I still sometimes get it wrong. But I’ve significantly reduced the number of “what was I thinking?” moments. It’s a bit of a pain that it requires this much effort, because their clothes are genuinely nice when they fit well. But hey, that’s the world of fashion sizing for you, I guess. Hopefully, sharing my little journey through the Theory sizing maze helps someone else out there feel a bit less lost!
