How do I calculate my dpo?

Question

From this app it tells me my fertile window, when do I start that I actually ovulated and go off of when to test?

Answer

You can track ovulation with OPK's. once you get a positive OPK you ovulate 12-36 hours after.
If you are tracking your BBT your temp drops after you have ovulated. 
Without some form of tracking all you can do is estimate when you have ovulated so you wouldn't know your exact dpo. 
Usually test around 12 dpo, which for me is roughly when AF is due from the length of my cycles. 
Good luck!

Answer

If you're going off of just when your fertile window is, ovulation usually happens the second to last day of the fertile window

How do I calculate my dpo?

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