I don’t have a measurement for you but it’s definitely pretty thick front to back. Personally I like it and I have really small hands. Fender specs say its 1 3/4” wide at the nut but mine is 1 5/8”.
I never thought I’d like a neck that thick but I do. My fretting hand seems to get fatigued less and I don’t find it any more difficult to play than my basses that have thinner necks.
I have another pbass that also has a 1 5/8” nut width but is much thinner front to back and for me the Harris neck is WAY more comfortable. YMMV.
It's been a LONG time since I played a stingray so I can't help you with a direct comparison.