Does gaining muscle mean you go up in clothes sizes?

Depends. How much muscle we talkin?

Most likely the answer is NO

I apologize if this sounds like a stupid question but.....
I have started doing squats, etc on non consecutive days of the week, combined with cardio about as often. I'm currently a size 12, my muscles aren't going to get huge obviously because i'm not training all the time, so I assume this means i'll be gaining muscle and losing fat as i know you can't just turn fat into muscle. Does this mean i will start going up or down in clothes sizing?
thanks

You might be losing fat, but with minimal training/no eating at a surplus, you're not gaining muscle. You're most likely retaining lean body mass.

If all your Ts are crossed and Is are dotted when it comes to training and diet, you'll most likely go down in clothing size even though the scale might not change as quickly. There maaaay be periods of time where your clothes fit a bit snug (from water retention from starting a new lifting program), but in general, your clothing size won't go up. Unless you're eating too much.

Gaining muscle at a deficit will make you lean, therefore you will go down on sizes. If you train hard and eat at a surplus then you will go up.

I have lost about 30 lbs with lifting weights (moderate, nothing heavy) and I went from a size 8 to a size 2. Now, since I've lost the weight I've been working in gaining some muscle, so I increased my calories a bit and have increased protein/carb intake and I have gotten bigger. My back is wider and therefore some of my x-small tops are getting thight under my arms, which I don't mind. So it all depends on what you are working for, if you are afraid of bulking don't worry about it unless you are eating too many calories and lifting for that purpose.

Good luck

I've lost about 7% body fat in the last 7 months and have only lost 3-4 pounds in the process, so I guess technically I was eating at a deficit because I never went through a bulk and cut, just a small deficit on my recovery days. I recomped, gaining muscle, which people say you can't do, but whatever.

During this process, I've lost a clothing size. I am 5'5" 170ish and I wear a size 8 or 10 (usually medium bottoms and large tops). This is the same size range I previously wore at 145, so I would say based on my experience, you just become denser and more compact when you lift a lot unless you were previously small and are just adding muscle and not losing fat.