Do you want to know gestation length? 11 months
Or do you want to know how long labor lasts from start to finish? No more than a couple of hours after they lay down.
Let me know if you still have questions.
Total gestation is 340 days from the day of the breeding. There is a nifty little chart here:
that will help you figure out the time table for your horse.
Let me know if you still have questions about this. Or if you need more advice. If not, don't forget to accept my answer.