Q & Answer: Should My Double-Breasted Jacket Be Buttoned When I Sit?
Charles asks: I was curious about the etiquette of sitting down in a double-breasted suit jacket or sport coat.  Is one permitted to unbutton it, or is it customary to leave it buttoned?
There’s no hard-and-fast rule on this matter, but I can give you some guidelines.
Generally speaking, double-breasted coats look much better when closed. You just have to watch a couple of David Letterman monologues to confirm that. So while it’s not required that you stay buttoned, it probably looks best.
I wear a lot of double-breasted suits on stage, where I typically have to sit, and I find that mine settle best with the lower button open but the top and inside buttons buttoned. That’s what it looks like Cary Grant is doing above. Your mileage may vary of course - I know some folks who prefer to leave only their inside button closed, and some who leave them all done up.
When it comes down to brass tacks, balance a clean look with your own comfort, and make the call yourself.

Q & Answer: Should My Double-Breasted Jacket Be Buttoned When I Sit?

Charles asks: I was curious about the etiquette of sitting down in a double-breasted suit jacket or sport coat.  Is one permitted to unbutton it, or is it customary to leave it buttoned?

There’s no hard-and-fast rule on this matter, but I can give you some guidelines.

Generally speaking, double-breasted coats look much better when closed. You just have to watch a couple of David Letterman monologues to confirm that. So while it’s not required that you stay buttoned, it probably looks best.

I wear a lot of double-breasted suits on stage, where I typically have to sit, and I find that mine settle best with the lower button open but the top and inside buttons buttoned. That’s what it looks like Cary Grant is doing above. Your mileage may vary of course - I know some folks who prefer to leave only their inside button closed, and some who leave them all done up.

When it comes down to brass tacks, balance a clean look with your own comfort, and make the call yourself.