Three piece suits

[Guest]

I am considering the purchase of a three piece in order to add a twist to my usual two piece attire

May I ask, do the chest measurements on a jacket that is be worn with waistcoat differ from that of a jacket to be worn on its own?

Can one wear the three piece on colder days and then dispense with the waistcoat in warmer weather but it still look appropriate?

Many thanks in advance

[Guest]

The vest has to fit closely. Therefore, the tailor must make this allowance in cutting the coat and vest.

Generally, the coat made for a three piece will be a little roomier than a coat made for a two piece. This is to allow the vest which will take-up some bulk especially on a heavy cloth. However, the coat from the three piece can be worn sans vest.