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Lily - Your Personal Fertility Calculator

By Whimsical Inc.

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Lily is a remarkably powerful, yet beautiful and easy way to determine the fertile and infertile phases of your cycle. It is the perfect tool for you to learn more about your body, while being discreet, reliable, and absolutely private!

You want to learn more about Lily and how it works? Head over to for more detailed information!
Once there, make sure to take a quick look at our privacy policy as well. We are absolutely sure that you will love what you can read there!

Lily lets you evaluate your cycles either based on averages (comparable to the calendar method,) or based on your body's own symptoms using either FAM/NFP (Fertility Awareness Method/Natural Family Planning) from the US, or NFP (AG NFP) developed by workgroup NFP from Germany. Your choice!

Lily can be a great little helper for you to achieve your family planning goals, and it works incredibly well for both: women who are trying to conceive, as well as women who are trying to avoid a pregnancy. Lily is also used by many women who simply want to learn more about their own body!

Evaluating your cycles based on averages is easy as pie, but a little less accurate. And even though the evaluation of your cycles based on your body's own symptoms requires a little more effort, Lily will be able to evaluate your fertility much more accurately – which is especially important if you want to use Lily to help you avoid a pregnancy.

If you want to use Lily's averages-based evaluation method, you can start right out of the box. All you need is the starting day of your past period, or two.

To successfully evaluate your cycles using one of Lily's symptoms-based evaluation methods, all you need is a thermometer labeled for taking your basal body temperature with two decimals behind the dot for °C, or with one decimal for °F – and that's it! You don't need to know or learn any complicated rules, Lily will do the work for you!

Lily also includes these features:
• see the time you are most fertile during your cycle and an estimated for the begin of your next period
• predict your 12 upcoming cycles
• charting of your temperature (Fahrenheit or Celsius)
• charting of your cervical fluid and its changes throughout the cycle
• view your data in the graph and calendar and get detailed information for every day by the touch of a finger
• add details on your love life (with or without protection)
• record interferences that may have lead to higher temperatures
• record period flow and associated symptoms
• record your mood
• password-protect your data
• an extensive in-app help
• discreet name and icon to avoid awkward moments

You can unlock even more features with an in-app purchase (We do have to pay our bills somehow!):
• more tracking menus: Cervical Position, Secondary Symptoms, Custom Notes, Medication, Diary, LH/OPK Test Results, and Menopause Symptoms
• rearrange the 'Your Data' menu, as well as the ability to hide tracking menus you don't need
• a dark theme, including the ability to let Lily switch between the dark and the light theme automatically depending on the time of day or your display brightness
• print your charts and data via AirPrint, or export and send them as PDF documents via email to your physician or anyone else you like
• smart reminders that tell you whenever Lily still waits for important data
• custom reminders for anything you want
• change Lily's pink to any hue you like

Lily was not developed to diagnose, treat, prevent or cure any medical conditions. For any medical related questions, please see your physician.

By using Lily you agree that Whimsical Inc. does not guarantee the method of birth control or pregnancy achievement and is not to be hold liable for an unwanted pregnancy or the unsuccessful attempt to conceive.

What's New in Version 3.5

• Greatly improved legibility of all texts
• Lily’s graph now makes much better use of available screen space
• Improved accuracy of due date prediction
• Added the luteal phase to the symptom-based cycle evaluation info screen
• Squished some bugs
• Fixed a number of typos

If you like Lily, please consider leaving us a rating on the App Store – even if you've already done so in the past. Your ratings, even if it's just the stars and no text, help other women a lot to find Lily and to benefit from this natural and hormone-free way to plan your family.

iPhone Screenshots

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Customer Reviews

Best charting app!

As a long time NFP user, I've tried more than enough charting apps and can confidently say that Lily is by far my favorite. The color changing screen between bright/dark, depending on time of day, is a real lifesaver. Also, the predictions are accurate and the reminders work great. The only thing I'd love to see updated is the verbiage -- it's the same whether you're TTC or TTA, and it would be encouraging to those who are TTC for it to say things geared along that way (instead of 'your next period will most likely start on...', for example). Thanks so much for creating such a fantastic and helpful app!!

Editing my post to add suggestion: after a recent miscarriage, I can see that it would be helpful to be able to exclude certain cycles from your cycle averages (Your Cycles --> General Statistics). The stats from my two cycles after miscarriage are vastly different from my norm and have thrown everything off. Furthermore, if we could choose multiple cycles to read averages from those only (past 3 months, past 6 months...) that would really be awesome for long time users who are working to change their averages (i.e. lengthening luteal phase, etc). ✨

Best NFP App!

My husband and I have been talking my cycles since 1997 using a sympto-thermal method. I've tried other apps but this is THE BEST for interpreting current fertility dynamically. (I chose the NFP AG evaluation after inputting my past data and seeing how they worked out) I heard about Lily through an online article and concur that it is what couples need to help meet their family planning needs. I highly recommend purchasing the full version once you download the app to gain most insight into what your body is doing. It will allow you to share your cycles with anyone you choose, such as husband and on/gyn.

Exceeded (almost) every expectation!

This app is marvelous. Does such a great job of gathering and organizing the information necessary for following the Fertility Awareness Method of birth control. The UI is also the best I have found on the app store (if it's on there, I tried it). The PDF user manual/FAM rules is really handy to have downloaded from the app as well.

The recent overhaul of the app really addressed the majority of my issues with the app's organization and details. It is well thought out and well executed.

Lily - Your Personal Fertility Calculator
View in iTunes
  • Free
  • Category: Medical
  • Updated:
  • Version: 3.5
  • Size: 24.6 MB
  • Languages: English, German
  • Seller:
Rated 9+ for the following:
  • Infrequent/Mild Mature/Suggestive Themes

Compatibility: Requires iOS 8.1 or later. Compatible with iPhone, iPad, and iPod touch.

Customer Ratings

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Top In-App Purchases

  1. Unlock all Features$5.99