I'm 5'7" have a 42" chest but I wear L clothing. I go up one size to account for shrinkage when laundering and it still fits.

Buy clothing that fits you slightly loose than clothing that could be smaller after its been washed.

Rule of thumb advice is go up one size from what you think you should wear.

With some parkas, you may need to go the next size up to get the right fit.

For example, in Canada Goose, I would wear a M parka. But for my Chiliwack Bomber, I have to go up to XL to get the right fit.

Its just a guideline but it will help you find your clothing size that fits well.