How far off the ground? What style of home? I am not a designer but there is no real formula without context of several other design considerations.

Obviously...larger than if it's an 8' ceiling, but usually a better question for the architect.

Context is key.

Sorry guys, that was supposed to be 9’ ceilings. i had planned to put them at standard 6’8” door height. the house is a new farmhouse look with 9’ walls with 9/12 and 10/12 roof lunes. flat ceilings no vaults. trying to keep cost in check..

Elevation drawings will help you get advice.