Ava Temps vs bbt

Guest_1606891779079

How accurate are the Temps from ava? I am simply using it for temp ( ignoring all other data) I've also been using the femometer bbt. I understand that skin temp is lower. However. I'm not getting similar graphs between them. My bbt has went up 3 days in a row. (Ff gave crosshairs) however my ava temp has went down 3 days in a row. I was expecting ava to be the most accurate of the two but now I'm second guessing that.