Please what is the best size for a Birthday card invitation?

Question: Please what is the best size for a Birthday card invitation!?

Please, I'm going to design an Invitation Birthday card for my friend

But I don't know the best size (In CM or Inches)

Can help me!? please, necessary

thanksWww@QuestionHome@Com

Best Answer - Chosen by Asker:

For just a birthday invitation, unless you want to get really into details and such, I'd keep it little, like a 4!.25 x 5!.5 inch design!.
That's a quarterfold on a regular 8!.5 x 11 sheet of paper!.

Postcard size would also be a good option, I think that's like a 4x6(inches) or so!.

For my graduation invites I used 5!.5 x 8!.5 inch cards, half-sheet, and they turned out pretty nice, but smaller wouldn't have really hurt anything!.Www@QuestionHome@Com

a 6 inch invintation!Www@QuestionHome@Com