Once(A special period tracker‪)‬ 12+

Malang Studio Co. Ltd,

    • 4.3 • 55 Ratings
    • Free
    • Offers In-App Purchases



To all the women who need a calendar to write down upcoming period
To all the women who need a journal to manage irregular period cycle and cramp
To all the women who want to know ovulation, fertile, birth control, and possibility of pregnancy all in one calendar
To all the women who were bothered to mark their period on the calendar
To all the women who secretly recorded symptoms on their planner
Must-have! Period tracker, Once!
[Kept both simplicity and functionality of period tracker!]

** Estimated period calendar which gets more accurate as you use it!
Once automatically calculates your irregular period cycle and cramp smartly!
In the period calendar, you can view your estimated period, fertile which has high percentage of pregnancy, and ovulation, all in one-step! In the calendar history list, you can view all your past period cycle in one-step.

** Take care of your fertile and ovulation meticulously!
You can take care of yourself even better with the calendar which shows fertile, ovulation, and estimated period in a glimpse of eye!

** A widget which allows you to check precious data quickly!
The first period calendar ever! Check the important info (estimated period, ovulation, and percentage of pregnancy) more quickly and easily with our widget.

** Percentage of pregnancy calculated scientifically!
Based on egg’s duration of life, 24hrs, and sperms’ duration of life, 3~5 days, we indicate percentage of pregnancy “high” for one day before and after the ovulation, and “moderate” for fertile.

** The day you must be prepared! Prepare it in advance!
To make you not embarrassed on the day! We notify the important dates (estimated period, ovulation/fertile and whenever you want) you in advance with witty message and alarm. We provide the alarm function of contraception pills.

** Keep your precious daily data conveniently!
Keep your data easier than a journal. All your recorded period, intimate days, memo, and automatically calculated ovulation and fertile… and all other data… You only need to sign-up to keep them all!

** Not just your period, but your secret intimate days!
You can record your status and symptoms such as the first day of period and period cramps, whenever you want.
Once, which you can record all your secrets such as intimate days! Don’t worry about others having a look at your diary, with our lock function.

** Simple and stylish design capturing women’s mind!
“The better it looks, the more convenient to use.” We have enhanced usability of calendar, by simple and stylish design. In the period calendar, you can view your estimated period, and ovulation, all in one-step. Just like a pretty planner you want to show off, the calendar design won’t be embarrass you even when you install it!

[We have added special features only available in Once!]

** Charming and interesting “Today’s Tip”, which changes depending on your cycle!
Beauty tips which makes you attractive and charming depending on period cycle, ovulation, and fertile. Useful real-life know-hows, useful diet tips, tips to prevent pregnancy, tips for healthy relationships… we enhance your charm by providing various tips!

** Once events made exclusively for women!
Staring from Once beauty pouch fully packed with sense, and Once doctor which provides exact information on diet and health… We hold various events on beauty, diet, and health, which suits women’s appetite!


Please be with Once, we are doing our best to bring you the best service :D
Developer: Malang Studio (http://malangstudio.com/)

* You can get faster response for questions regarding Once if you write to once@malang.kr!

This service includes In-app Purchase items, and a separate fee will be charged for purchase.

- Terms of Service : https://bit.ly/38zBlvj
- Privacy Policy : https://bit.ly/3iqaZ3g

Tel. support@malang.kr / +827050386396
Address. 11th floor, 508, Eonju-ro, Gangnam-gu, Seoul, Republic of Korea

What’s New

Version 1.7.9

fixed bugs.

Ratings and Reviews

4.3 out of 5
55 Ratings

55 Ratings

Parisasmart ,


I like this app, thank you Once🤩

Developer Response ,

Hello, this is Once Team :) First of all, we'd like to thank you for your interest in our service. Also, we're so glad to hear your compliment! We'll do our best to keep our service the best as we can! Thank you so much, and have a good day :)

Jennifeeeeerrrr! ,


This app is great. It's pretty discreet I'd say. The only con to this app is that it resets every time you login on a different device.

Update as of August 2020: I’ve been using this app for at least 5 years, but I’m not sure exactly how long due to it resetting in past versions. Now it syncs if you happen to get a new phone or something. They added a lock to get into the app, which I really like but you can disable it if you don’t want it. Still by far the best tracking app I’ve ever had. I don’t track my symptoms anymore unless they’re really bad, so I’m not using it to it’s full potential at times, but I absolutely love that I can look back on all my past symptoms/notes. I love that it can adjust how long your period should last based on previous periods.

If I could add anything, I would add the option to create your own symptoms, and maybe a feature that tells you when to expect cramps/other symptoms based on when you typically have them.

hdhfvhgfhhvg ,

Best app

I’ve been using this app for maybe 5 years now. All the other apps don’t track my period as good as this one does. This one seems to always be on time, the others always are off. The only thing I would change is that it would be cool to “add a partner” so that they knew when you’re on your period or about to start. I like that you can personalize your notifications for when you’re ovulating or about to start your period. “Shark week is coming” is always a hit.

App Privacy

The developer, Malang Studio Co. Ltd,, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Used to Track You

The following data may be used to track you across apps and websites owned by other companies:

  • User Content

Data Linked to You

The following data may be collected and linked to your identity:

  • Contact Info
  • User Content

Data Not Linked to You

The following data may be collected but it is not linked to your identity:

  • Health & Fitness
  • User Content
  • Identifiers
  • Usage Data
  • Sensitive Info
  • Diagnostics

Privacy practices may vary, for example, based on the features you use or your age. Learn More

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