Code requirement: 15", recommended: 18". Also pay attention to the required space in front of a toilet.

See The Illustrated Rules of Good Bathroom Design for more information.

My design book says that there should be a minimum 24" "activity space" in front of a toilet. You'd only have 33" + 12" = 45" in front of the toilet which is not enough for a bathtub (typically 60" long minimum). (The 15-18" above refers to the distance between the center-line of the toilet and the walls on either side).

With a bunch of plumbing work, how about reducing the vanity length and moving the toilet between the vanity and the adjacent wall?

-- amateur

Not only did you help me answer that question, I found more answers on your website. Thank you so much.

Wdcruise, thank you. sorry it took me so long. I am not getting all of my notifications when someone replies.

The hall closet used to contain the original furnace so it needs a new floor and needs drywalled. I would rather keep it deep, but I could make it more shallow to give me room for a tub. Maybe move the back closet wall about 15-18"? 18" + 33" +3" (frame of current shower) = 54" + I have 36" to the outside rim of toilet. Should be enough for a tub.

The only reason I want a tub/shower is because it will be less expensive and easier to install a tub. We live in a rural area and very few contractors here know what they are doing. We have not found anyone yet who knows how to install a tile floor in a shower correctly. (We asked how they would do it and what materials they would use.) So a tub would be less problematic for the contractor.

The current shower has a center drain. I guess I will need to find a new shower with a center drain or have the drain moved for a new shower or tub. The house is on a slab so I have no idea what moving the plumbing would cost.