How long is a bouquet of a dozen roses?

There is no set amount of roses in a bouquet. Everyone have different sizes of bouquet.

It depends on the types of flowers you are using, or what kind of look you are going for. It also depends on the person..if you are a tiny person you wouldn't want to be carrying a huge bouquet or it would make you look even smaller (This would apply to a wedding of course).

If it's going to be a bouquet in a vase or for an arrangement then it would depend on the vase/arrangement ...sometimes it looks good to overfill and overflow and sometimes it looks good with very few.

If you are doing this on your own it is all up to personal taste...if a florist is doing it for you then don't worry about it! :)