Definitely 1/2" for the fixed and "maybe" 3/8" for the door. Maybe depending on your installer feels about mixing.

As @millworkman says. I would rely on my fabricator shower door contractor opinion of strength vs price. We'll mix when 1/2" is needed for stability.

Have you considered what type of glass you will use? Standard glass or low iron?

millworkman and Jeffrey R. Grenz, General Contractor, thank you for the advice. My main contact at the fabricator told me he recommends 1/2 here for both, but the guy that came out to measure said 3/8. mark1993 brings up a new layer with the glass choice - the quote is for standard glass. Should I consider low iron?

@kharten The reason I bring it up is because we are building a new house. I chose Showerguard glass coating, and then I learned about low iron glass. I researched the difference between regular and low iron and realized how much better I liked the low iron. Regular glass has a green tint. Since our shower has a window and white tile, I didn’t want the green tint. Even though it’s pricier, to me it is worth it.

Agreed, I used low iron glass too. You spend so much time agonizing about tile colors for a shower and then you put a green tinted glass in front of it all!!

mark1993 and chispa I'm trying to find pictures of showers with standard glass and I'm not having any luck. Would you happen to have any that you could share with me? I have a white tile shower, but the bathroom does not get a lot of natural light

mark1993 and chispa I'm trying to find pictures of showers with standard glass and I'm not having any luck. Would you happen to have any that you could share with me? I have a white tile shower, but the bathroom does not get a lot of natural light

This link does a good job of showing the difference of the low iron versus regular glass.

I support the low iron comments here. It is more expensive but worth it in my opinion. I have no regrets.

@kharten I believe the above photo is standard glass because of the greenish tint.