I take 10,000 IU of Vit D3 a day. Last summer my level was 85 ng/ml and my doctor thought it was too high and wanted to recheck it in 6 months. That put me into winter and my level had gone down to 59 ng/ml. The sun took me up to where I wanted to be, but being inside brought it way down without changing the dosage. So I would say that the time of year will also change your results. I still take the 10,000.