Three-button suit

formal occasions three buttons fastened, less formal one button, and informal no buttons!

I have been wearing suits for many years. There are no rules for how many buttons to use, some people will say if you have a 3 or 4 button suit you leave the bottom one or the top one unbuttoned, but I usually button them all when I do button them. Most of the time my jacket is not buttoned at all, it is just more comfortable for me opened.

Out of curiousity I researched this question and found an article that discusses the matter in great detail. It summarized this way: Two button suit: button only the top button. NEVER button the lower one. Three button suit: button either the middle button alone or the top two buttons. Again, never button the bottom button.

Never button the bottom button, this goes for jackets and button-up shirts. All other buttons are optional- do what looks best on you. I got for the middle button out of laziness. It's much easier to undo and button one button when sitting down and standing up. 

I work in a "suit" corporation and most men will leave the bottom button open and button the rest.

i had the bottom button undone and this man unbuttoned the top one as well. only the middle one was buttoned

i hope it is correct like i said because i am going to function next week.

The etiquette of men's dressing says that only the middle button should be tied. It is easier to sit that way, and that button should be tied especially at the conference table.