Calendar 1 Year 12 Months is a free, easy-to-use calendar application for Android users. It displays the current year and the next year, with the ability to change the year using the left and right buttons. The first day of the week can be switched between Sunday and Monday, and today's date is highlighted for easy reference.

In addition to these features, the app also displays monthly week numbers and allows users to set their own holidays with year/month/day or month/day designation. This is helpful for keeping track of national holidays, constipation, menstruation, and even the full moon. Users can also adjust the screen width (font size) to their liking. Overall, Calendar 1 Year 12 Months is a simple yet useful tool for anyone looking for a free, perpetual annual calendar app.