Can you calculate when you're ovulating?

Yes - roughly: Ovulation calculation can be reasonably accurate within a few days. I suggest tracking several cycles. Count 14d back from menses, look for day of BBT increase and ovulation day before, OPK gives 12-24hr advanced warning. Do this is you are planning pregnancy to time sex (helpful to me if you need help). Natural family planning has a high failure for most people. Best wishes.

12 days before flow: In women with regular menstrual cycles, ovulation happens 10-14 days before the next menstrual flow. If cycles are regular and 28 days, then ovulation happens around day 13-15. If cycles are irregular, ovulation can be tough to time, and indeed might not happen at all.

14 days before: An easy way to remember ovulation is that it occurs 14 days before your next cycle. If you know how many days between periods then you can calculate an approximate ovulation date.