what its a business size envelope?

Answer 1

I believe it's 9 1/2inches long by 4 1/4 inches High.This is the size of envelope most of your bills come in

Answer 2

It's the same size as the regular mail envelope. It's called a #10 envelope. If you go to staples or any office supply store they will be able to help you.

You can use the regular envelope, but there are also business envelopes with a window (rectangle cutout) for the receiver, and there is another one that has a window for both the sender and the receiver. That one is for mail that you print out your address and the receivers address on.

Hope that helps