Kalkulator Masa Subur is an Android application developed by Hello Doc that falls under the Lifestyle category with a subcategory of Health & Fitness. This free application is designed to help couples who are trying to conceive or have a baby program. The app uses a medically proven formula to calculate the fertile period of a woman based on two data points: the First Day of Last Menstruation (HPHT) and Menstrual Cycle. With this app, there is no need to manually go through the calendar to calculate the fertile period. The app is compatible with Android 9.0 and provides an accurate and successful calculation of the fertile period.