oops here is a better picture of the windows

Hi Starmint9!
We specialize in lighting for high ceiling spaces and foyers. We carry beautiful fused glass lighting that can be designed in different sizes, length and colors.
We advise our customers about the right size of chandelier for their space.
to receive our catalog by email you can contact Sales@GalileeLighting.com
We deliver worldwide.

I just measured my foyer (picture on the left) where the light the builder put in is 13' tall
over a 5x5 landing (standard colonial two story foyer) except the light is
a bit over the stairs. I am not sure what area should be considered a
measure. I think the height is fine if I got a 28" chandelier but would a
28" wide chandelier be too big? It seems like it will not be too big for
the window but I am unsure if I should go narrower of it it's ok to go
bigger for the foyer. (better than too small)

If you want it to show through the window you should probably stay within the footprint of the window. I like Prestige's suggestion for a pair from the same collection. I also think they'll hang at different heights if you want them to show through the windows.

Do I need to stick to the rule of thumb about the size though? The current dimensions are saying I need a 15 inch chandelier which is very small

Hello Starmint,
Your footprint of your landing is 60"w... so rule of thumb for that "space" is no more than 30"w. But your window seems to be only 36"wide (hence, why you may feel 28-30" is too wide) So, you'll need to choose whether you want it to be wider than your window. Or just the width of that window. Both would be appropriate. Just your preference.

Thank you! I appreciate it this is the most difficult task. But I am learning a lot. Thanks again :)

I agree with Prestige Lighting & Design in regards to using fixtures from the same family but with different shapes - What a great idea!! Also, thank you for the information on the rule of thumb in regards to lighting that space.. I didn't know that! Much appreciated! :)

Sorry to bother, but can I ask the calculation of the landing? I am getting 5'+5'=10 inches because I thought you added them up to get the total number of inches that the diameter should be. This is what I see on all other web sites.

Hello Starmint,
Not sure what calculations are out there... I have used this symmetrical formula..which has been successful for my lighting design of spaces.
5 foot across the wall with the window? Correct? That would be 60"...So 1/2 would be 30".
We try not to have hanging lighting more than 1/2 the width of any wall/floor space. Any larger takes over the space! That would put your maximum 30"wide fixture dead center of your space leaving 12-16" on each side. If you cut a piece of cardboard the height and width of your chandelier and hang or hold up in that space I thing you will feel more confident in your decision of what size fit best for you! All above are just my suggestions! Hope it helps!

that helps a lot. thanks!