You can calculate you age as much as possible in details.

It only needs a name and date of birth of your friends or family members.

You can know your age in year, month, day and also upcoming birthdays and remaining time for next birthday.

Extra is all totals (years, months, days, weeks, hours, minutes, seconds).

In details, you can also edit name and dates of birth you added and if you want, you can delete it.

You can sort persons you added so many way as possible and also search in app bar directly.

You can see persons you added by months by, weeks by and days by alternatively.

You can also compare two persons how difference in age.

App size is more lightweight than normal.

Free and open source
https://github.com/hlayan/birthdays-master

Finally, In my app, you can really change theme color a lot.