When Building A Bird House, What Size Hole Do I Need For An Opening For A Finch?

After careful consideration concerning the size of the opening , I must say that if it is a female bird , and if she is caring all the stuff that my wife carries when we go off for the night , the hole needs to be as big as possible . But to be truthful and honest the correct size of the hole for a finch is one inch , the size for a blue bird is 1 5/8 inch and etc.
                                                      Thanks ,

                                                                        the bird man

Depending on the type of finches you keep you'll need an entry hole of approximately 4-5cm (1.5-2inches). This tends to be the average size of the commercially sold finch breeding boxes.

Hope this helps

Yes, you don't want to make the hole too big. It would result in larger birds or even squirrels venturing into the bird house.