That's a lot. Vitamin D tests are easy to get, so I just took a few over a few months to find a dose that would keep me at ~50ng/ml. Previous to that, I had taken 5000+ IU/day for some time and the test showed my levels were very high.

It looks like this site has a nice chart: https://www.vitamindcouncil.org/further-topics/i-tested-my-v...