Iron Supplements

For the treatment of iron deficiency, the recommended oral dose in adults is about 150 - 200 mg per day of elemental iron. The key thing to notice is elemental iron since iron supplements come in multiple formulations. A box of ferrous sulfate 325 mg might look like it could be your whole daily dose, but there is actually only 65 mg of elemental iron per tablet.

Treatment of the adult with iron deficiency anemia. UpToDate 2014