iPhone Screenshots


Get the best Ovulation and Pregnancy Calendar now! OP Calendar predicts your fertility window by tracking your periods so that you can plan ahead for pregnancy. Use your fertile or less fertile days to your advantage, and take the guesswork out of family planning.

1.Easy to understand user interface
2.Accurately predict your future periods and fertility windows
3.Keep track of your last “fun” encounter
4.Predict your due date if a baby was conceived
5.Custom color choices for high and low fertility days
6.Optional passcode to protect your privacy

The interface is simple to understand and custom color-coded. High fertility days can be shown as green and low fertility days can be shown as red, or vice versa, depending on what is most intuitive to you. This feature is very unique, as other apps have non-custom colors that can be confusing.

Upon inputting the beginning and end of your menstrual cycle, the app does all the complicated calculations for you so you know which days of the month you can let loose and have unprotected “fun” and which days to avoid. The app also incorporates the latest gender prediction theories to let you know which days may result in the conception of a boy or girl.

Menstrual periods and ovulation cycles vary from woman to woman and month to month. This tool should be used as an estimate only and not as a replacement for professional medical advice.

What's New

Version 1.2

Added color-coding switch
New supported language: Russian

Ratings and Reviews

4 out of 5

151 Ratings

151 Ratings

Really Not Helpful At All


I downloaded this app because it seemed more simple than the competitor's apps and I thought I would like it a lot more. I have a very irregular cycle so I learned quickly this app isn't very accurate in recording pretty much anything, and a month after I started using it you guys took the calendar function away. What good is the app if I have to scroll through every single day of the year to look at when my period started, ended, etc. I NEED an app that simpler allows me to look at a freakin' calendar overview like ALL the other apps JUST like this one do, except their apps are actually useful. I'll be writing down my data from the app, transferring it to another FREE app that offers FREE access to a FREE calendar. Thanks anyways but it seems like you as the developers have quite a bit of work to do in order to make this app something that I would even consider using again. But probably not.

I'm pregnant!!


I got my Paraguard IUD removed in November 2013, and began using this app to track my menstrual cycle in December 2013, which is when I learned about it. I found out on January 21, 2014, that I'm pregnant!! This app was extremely helpful for my husband and I to try to conceive and I really don't think we would've gotten pregnant this quickly if we weren't able to figure out with this app exactly when I was fertile and ovulating. I recommend this app for sure! Give it a couple of months so you can see if your cycle is regular or not, which is very helpful to figure out.

great app!


this app is very accurate with the timing of my cycle! I use it to track my ovulation schedule so that we can be extra safe, along with birth control to avoid any "oopsie babies". I was a little hesitant at first as to whether or not it was accurate. I start the day it says I am supposed to and usually when I am ovulating I can feel it and I look at the app to see if I'm supposed to be and it's right on schedule! Good app for planning pregnancy and avoiding it! lol


2.3 MB
Requires iOS 5.0 or later. Compatible with iPhone, iPad, and iPod touch.
English, French, German, Japanese, Russian, Simplified Chinese, Spanish, Traditional Chinese
Age Rating
Rated 4+
© Nighp Software 2013
In-App Purchases
  1. OP Calendar Full Version $2.99


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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