Best app for ovulation prediction?

[tooimpatient2]

I use period calender, flo and Ovia but they all show different days. Just wondered if anyone has found one of these to match up to their OPK's?

Hi, I'm not using OPKs next cycle but I've used Natural Cycles for over 3 years and found it to be very accurate, even with my irregular cycles (it takes any irregularity into account). You just temp x

I've used natural cycles for years. Simple and accurate.