Sitting down in a suit jacket...

Single breasted: unbuttoned.
Double breasted: buttoned.

Are you meant to keep a double breasted suit buttoned when you sit down, I tend to unbotton mine is that wrong?

Cheers Nick

Afaik, it's that: unbuttoned DB look weird. Then again, if it's too hot, just take it off.

There is a thread on this...but yes, I do(I am now.) Unbuttoned as I don't really wear 2ble breasted...

+1
/thread

For me the general rule is:

Single B - unbutton upon sitting and button immediately upon standing. This has become so much a habit for me that I do it without thinking about it. This should become the same for you - as you want to look confident and relaxed in your clothing - not uncertain and uncomfortable.

Double B - leave it buttoned.

However, there are some very formal situations in which unbuttoning a Single B upon sitting might be considered too casual. (Board meetings, some foreign locales, etc. etc.) .

Whenever in any unfamiliar situation I always follow my mother's sound advice regarding all forms of etiquette - pay close attention to the host and those around you and simply follow their lead.

Pretty much the same for me. One thing I'll add is that if I'm about to be introduced to give a speech or presentation I'll leave my sb buttoned while sitting so that I won't have to worry about buttoning it when I stand.

Unbottened when sitting. Buttoned while standing.

Only casual.

NEVER if it's a suit the jacket is buttoned while standing - no exceptions.

Sport coats with ties - the same - no exceptions.

Sport coats without ties - well your off into the gray areas there and I say do it how you like it! Although I'm pretty likely to button unless it's a cotton sport coat with jeans or some other very casual use.

DON'T MAKE ME COME AND TAKE YOUR STYLEFORUM CARD AWAY FROM YOU - GOT IT?

Far too much sensitivity and too many history lessons here.

Traditionally you would be taught to unfasten when seated, fasten when standing etc. Now the former still remains appropriate for comfort, the latter, frankly, is quite outmoded. Bear in mind that at one tome offices were cold unheated places, now quite the reverse and wearing a coat safe when arriving or departing is too much. Board meetings these days lack the formality of days gone by and tend to be easier gatherings where those present are more equals with a job to be done and discussions held as opposed to being old fashioned wooden rubber stamping sessions. Few pompous chairmen might like to dwell on days gone by but that is more to do with their over-blown egos than reality. I would certainly never fuss and prefer those present to be comfortable than look like something from the 1950s for the camera.

It matters little whether it is double or single breasted although the extra bulk of a db is sometimes better managed with the inner button fastened.

This.

At the forward fitting my tailor sets the buttoning point of my DB's when I'm seated so they lay correctly when I'm sitting. I also get some flare to the skirt for the same reason (and I think it looks cool).