What size surround for a 32 inch tub?

I was at Lowe's the other day and found surrounds that were 29 and 32 inches deep. I measured the tub I have and found that it was 30 inches from the lip to the front of the tub. It was actually 29 1/2 but I added the 1/2 for the drywall.

What size surround should I be looking for here? I'm probably going to go with a direct to stud installation.

It depends on what you are doing. If you buy a new surround it will have instructions with dimensions that are required showing where the studs should be when building an alcove.

If you are installing in an existing alcove, it will depend on the configuration of the walls and your personal preference. Consider how far out the surround should be to protect the surrounding wall and don't overlook that you or someone else might want to install shower doors if they are not there now.

The alcove exists, as does the tub, it just needs a surround. Definitely won't be needing a shower door. I was just under the impression that you'd normally make it flush with the tub, but I guess that's not always the case?

You will only want, or need, a 30" surround, since anything wider would have to go down to the floor in front of the tub, and none of them come that long. Which one you use depends on how it installs. A 32" one which overlaps might also fit a 30" tub, you have to check on what its min/max dimensions are.