Physical examination was unremarkable: there was no palpable adenopathy; breath sounds were clear to auscultation bilaterally in all lung fields; there were no appreciable murmurs, rubs, or gallops; there was no organomegaly or tenderness on abdominal examination; there were no appreciable rashes on examination of the skin; and there were no sensory ...
1 Each follicle contains an immature egg (ovum) but only one follicle usually survives to maturity. It is supposed that ovulation pain is caused by the expanding follicle stretching the membrane of the ovary.  Ruptured follicle - when the egg is mature, it bursts from the follicle. This may cause slight bleeding.
In brief: A few days. Pain related directly to ovulation, sometimes called mittelschmerz, ' is usually only a few days. Obviously there is personal variability, but one or two days is very common. There can be pain indirectly related to ovulation or not related at all that might make pain go on longer. I suggest if pain lasts longer than about 4 days checking with a doctor may be helpful.