If you want to calculate age in month you can use this method . In this method pass dob year,dob month & dob date.

public int monthsBetweenDates(int year, int month, int day) {

        Calendar dob = Calendar.getInstance();
        dob.set(year, month, day);

        Calendar today = Calendar.getInstance();

        int monthsBetween = 0;
        int dateDiff = today.get(Calendar.DAY_OF_MONTH) - dob.get(Calendar.DAY_OF_MONTH);

        if (dateDiff < 0) {
            int borrrow = today.getActualMaximum(Calendar.DAY_OF_MONTH);
            dateDiff = (today.get(Calendar.DAY_OF_MONTH) + borrrow) - dob.get(Calendar.DAY_OF_MONTH);
            monthsBetween--;

            if (dateDiff > 0) {
                monthsBetween++;
            }
        } else {
            monthsBetween++;
        }
        monthsBetween += today.get(Calendar.MONTH) - dob.get(Calendar.MONTH);
        monthsBetween += (today.get(Calendar.YEAR) - dob.get(Calendar.YEAR)) * 12;
        return monthsBetween;
    }