What is the recommended dosage of b12 per day please give dosage in mg not mcg?

0.024 mg: The rda for B12 is 0.0024 mg (2.4 mcg) for adults, 0.0026mg if pregnant and 0.0028 mg if if breastfeeding. Because 0.0024 is so low it is commonly written as mcgs instead of mgs. 1 mg=1000 mcg. However, B12 is poorly absorbed, so if you take 500 mcg (1/2 mg) of a B12 supplement only about 10 mcg (0.01 mg) is absorbed. See http://ods.Od.Nih.Gov/factsheets/vitaminb12-healthprofessional/.