I found that taking two magnesium tablets per day eliminated my painful leg cramps. After a few years, I thought maybe I could get along with just one a day, but then I soon began experiencing cramps again. So being an intelligent person (usually) I'm back to two per day, one in the morning and another with my evening meal. The magnesium supplement I take is "High Absorption Magnesium" by Doctor's Best, but I suspect there are other good brands as well.
Best wishes!