Nolvadex Dosage

I’ve got some liquid nolvadex that says it’s 33mg/ml. The dropper with it has no markings. Was thinking of starting at 20mg but how many ml would that be? I’ve looked all over and kind find anything that helps.

If 1ml = 33mg then
1/3ml=11mg
2/3ml=22mg
3/3ml or 1ml=33mg