Ok, this is a bit of a random one. I'm still waiting to get my prescription for T (on the NHS) but will probably be going on in about a month! And I just had this strange thought... So a neighbour just rang my doorbell, and most of the time when I'm just chillin at home I don't bother wearing a binder, and there's not exactly time to put one on when someone's at the door (people give up quickly after ringing our bell for some reason) so when I go up to answer the door I'm usually not wearing a binder. And at the moment it's not really a thing, people still think I'm a woman, the tits are to be expected, whatever (at the moment no one recognises me as a guy unless I explicitly tell them, probably because of my height, my voice, and maybe my baby face. I think I dress to hide my hips but who knows what people are going on when they gender me in the street). It just occurred to me that in a few months I'm gonna start passing more, and I wondered if I'm going to be in this weird situation where I'm clearly a guy, but... well... you know. Moobs.

I know that taking T makes your chest flatten a little bit on its own, and I've seen loads of pictures of skinny guys who look like if they just put a loose top on they're not really noticeable unless you're looking for it. I guess I was wondering about bigger guys. I'm a little overweight and if I remember correctly my bra size used to be something like 38DD, so they're bigger than average. I guess what I'm really asking here is how much do they shrink, really? If I throw on a hoodie will it still be obvious like it is now that I'm not wearing a binder? I know that your milage may vary and all that stuff, but I'm curious.

tl;dr if you have a large chest, how much did it go down after starting testosterone?

If you're a bigger dude, I wouldn't expect anything. I had no change in size whatsoever between starting T and top surgery. Mind you, it was only 5 months before I got them lobbed off, but still.

The only things that might make a difference are building pectoral muscles and losing weight in general. The chest and butt are usually the first two places that you'll see weight loss from. If you were to go a significant length of time on T without top surgery, you could also hope for some fat to redistribute from your chest to elsewhere, but I wouldn't imagine that it would be to the point that you could go binderless and still pass as male.

bleh that's rubbish. guess i'll just be confusing my postman

I'm eight months on, and my partner says my chest looks smaller...though I don't really see it, and attribute it to binding and not the T itself.

Thanks for asking that question.  I was wondering myself, being also, rather a large guy up top. I'm kind of concerned about looking like a bearded woman after I start T, but I'm hoping that my top surgery will shortly follow.