How long do pinto beans need to soak?
4 hours - but you can soak them overnight if that's easier.
I don't soak pinto beans, I boil them for about 3 minutes and take off burner and let them sit for an hour and then cook.
FYI, the quick soak that SKK describes is great, and makes the timeline manageable. I once put beans on in the morning, got them boiling and left for work. By the time I remembered, hours later, and drove the 2 miles home, the house was full of smoke, the heavy pot had fused to the burner, and -- obviously -- the beans were charcoal. The burner could be saved but the pot could not, and I'm just lucky I didn't burn the house down! So be sure you follow step 2, 'take off burner.' We had something else for dinner.