It’s per kg, but I can help you with the conversion / calculation:
So if your little one is 12 months old, the recommended dosage of Prevacid would be 1 – 1.25 mg/kg/dose given 3 times a day. And 22 lbs would be equivalent to 10 kg (1 pound is 0.455 kilograms). So for a 10 kg, 12 month old baby, the minimum recommended dose is 10 mg 3 times a day (30 mg total per 24 hours), and the maximum recommended dose is 12.5 mg 3 times a day (37.5 mg total per 24 hours).
Hope that helps!