How accurate are period and ovulation tracking apps?

[Anonymous]

My Period was on the 19th through the 23rd in June and my Boyfriend accidentally came in me 4 days later but didn't tell me until a week later. I use a period and ovulation tracker app and it said my ovulation day was July 7th and my fertal window was July 2nd to July 8th how accurate are these period and ovulation tracker apps?

[Emilyis]

I have never used them but I have friends that have and they say they are GREAT!

[Subarugirl]

If you been using it constantly for a while it is pretty accurate

[__MisterGoneShiner__]

A little to none.