This will depend on the intake and weight of child. For children starting out, a 2oz bottle of Liver Life will last approximately 2 months and a 4oz bottle approximately 4 months. At 15 drops, 2x a day, a 2oz bottle lasts about 50 days; a 4oz, 100 days. At 1 dropper, 2x a day, a 2oz bottle lasts about 30 days; a 4oz, 60 days. At 2 droppers, 2x a day, a 2oz bottle lasts about 15 days; a 4oz 30 days.