Google Calendar is a great tool for you to add schedule and get organized. If you are following another calendar in addition to the default Gregorian Calendar, such as the Hijri or Chinese calendar, Google does allow you to display them alongside the default calendar.
Go to Google Calendar and click the “Cog” button, followed by “Settings”.
Scroll down the page until you see the section “Alternate Calendar”. The default option is “No alternate calendar”. You can change it to Hijri or Chinese Lunar Calendar.
Once that is done, click “Save” and go back to calendar, you should see the date of your selected calendar showing up side by side in Google Calendar.
If the calendar that you are looking for is not in the “alternate calendar” list, you can go to “Calendar” tab in the Settings page and click “Browse Interesting Calendar”.
Go to the “More” tab and you will be able to add Hebrew Calendar, Day of the Year, Phase of the Moon, Stardates etc.