Is there a "formula" for how wide a stationary drapery rod should be? Is it based on the size of the window? 95"wide by 45" high.

I don't think there is necessarily a formula. It depends on the look your going for. I have French country so I use less than 1" diameter iron or metal rods and hang curtains with rings. If your using grommets I think of that as more contemporary and would go for a little larger diameter something at least 1" to 1.5". There are some wood rods that have large diameters around 2" and those can be pretty heavy looking. But it is a personal taste thing.

Grommet-ed panels have a pretty small "stack" (when they are open, how much room they take up) I typically like for stationary panels to look full enough, that if pulled closed - they would actually work to cover the window. with a 95" wide window, you would want two panels per side. Now, to answer the width of the rod question - if you want to make your window appear larger, then you want to have enough rod to allow the stack to sit next to the window, rather than in front of the window. Probably 10 - 12" past the glass on each side. Also try to find panels that are long enough to be able to mount the rods as high as possible, and still allow the hem to brush the floor.

Thank you! I was thinking of those small short rods, rather than 1 long one across the entire window. Definitely want to mount the rods as high as possible. Like these:

[https://www.houzz.com/photos/family-rooms-traditional-family-room-minneapolis-phvw-vp~163495 [(https://www.houzz.com/photos/family-rooms-traditional-family-room-minneapolis-phvw-vp~163495)

My bad. I thought by "wide" you were referring to diameter of the rod sorry for misunderstanding.