Original Source: https://theblacktux.com/blog/how-to-measure-for-a-suit/
The fit of your suit really comes down to personal preference. If it helps, think about the fit of a suit like you’d think about eggs: not everyone loves them the same way, so unless you specify, you might get scrambled when you’re expecting sunny side up.
CLASSIC VS. REGULAR VS. SLIM VS. SKINNY FITS
Each brand will interpret fit types in different ways, but generally, there are some assumptions you can make about classic, regular, slim and skinny fits.
Classic Fit
A “classic” fit will be more generous in size overall. Rather than having a contoured cut, you’ll find the waist of the jacket and leg of the pants to have a pretty even cut without much tapering. This fit had its heyday in the ’80s and ’90s, but some brands offer a modern version of the classic fit that’s just a little more generous in the seat and thigh of the pants, and in the arms of the jacket. You can expect the same from a “regular” fit.
Skinny Fit
A “skinny” fit is probably going to mean what you think it means: it will contour your body closely. This probably isn’t a great fit if you’re planning on… I don’t know, doing the YMCA or entering a limbo contest? That’s because this fit won’t leave you with much extra fabric (literally no wiggle room) in the jacket or pants. But if you’re going for a model-in-a-magazine look, skinny fit probably checks all the boxes. Just don’t plan on lifting any boxes.
Slim Fit
A “slim” fit offers the best of both worlds: a contoured cut that looks great, but with just enough room to shake your groove thing. It’s also timeless, so a very safe choice for fit if you’re purchasing a suit. The jacket will have a tapered waist, hugging you in all the right places, and the arm holes will neither feel baggy nor constrict your movement. Plus, the leg of the pant will taper down to your shoe, creating a slimming effect.