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Friday, 17 October 2025

Copying a Google Calendar from 2025 to 2026, part 1

Firstly, I would like to say that I am very grateful that Google calendar exists. It allows me to harmonise all my appointments across three systems: my 'trinity' selves. I invite myself at two workplaces, and to my cellphone - across three email addresses - using GCal as my Master calendar. It is a bit complicated, but I have managed to make most things work so I keep track of my commitments.

Secondly: I have a little niggle with GCal. I would love to have a way to "copy" this year's calendar to next year. I have not yet QUITE worked out how to copy one year's appointments in Google calendar to the next year, including moving all the appointments/events/tasks back one day so they all fall on the appropriate day of the week. I have been fiddling around the edges of this problem for years, and not really getting to a clear solution. However, recently I have got a bit closer to a solution.

It began with me posting a question on Google Calendar Help, earlier this year:

Copy Google Calendar Events from 2024 Calendar year to 2025 year
I am sure there must be a way to do this, but I cannot work it out. I am a lecturer. For each of the papers I teach, I create a sub-calendar in Google containing all the reminders, week numbers, assignment starts, topics, meetings and deadlines. However, I have not been able to successfully export LAST year's sub-calendar for each paper - say to Excel, change the dates to THIS year - then reimport it as a new sub-calendar into my master Google calendar. Is there a way? Can someone help?

I got a reply from Priya Chandra, who said that I could "use the export/import feature of Google Calendar to bulk edit events. This video shows you how to do that: https://youtu.be/hJdGBmHDafA", pointing me towards a GCalTools video (2020).

On watching the video, it showed me how to delete a calendar which was wrongly imported. It explained clearly how to export a calendar as an .ics file, open it in a text editor (like Notepad) and edit a repeating line of code to then reimport the calendar to bulk remove the wrongly imported entries (GCalTools, 2020).

While I didn't want to remove imported entries, the video made me think that perhaps I could export one of my calendars, change the dates to next year, and reimport the edited .ics file. I started trying to work out how to do that. I exported one paper's calendar, which had 48 calendar items. I opened the .ics in Notepad, highlighted the export data, and copied the resulting lines of code into Excel. Then I realised it was over 1000 lines long. Ouch.

OK. So maybe I should filter the entries to see if there was a logical set of entries with 2025 in them. That might help me decide which were the key lines of code I should edit to change the appointment dates. Ah: 255 lines containing 2025 for 48 appointments. And I might not need to edit all the lines...

I unfiltered. I could see no obvious 'master' lines for each calendar item. Hmm.... what if I create a 'test' calendar with a couple of different appointment types in it - one multi-day appointment, and one repeating appointment. If I exported the test calendar, I might be able to see what I should be looking for. I did that, and it worked PERFECTLY. It seemed that the lead entries for each new calendar item began with the following two prefix lines:

DTSTART

DTEND

Different types of calendar item had different text following those prefixes, but at least I knew what separated each appointment. Now all I needed to do was to work out which, and how many dates, I might need to change.

So I took another look at my test export data. I wondered what would happen if I only changed the DTSTART and DTEND dates. These were formatted as number strings with the year first, then the month, and lastly the date: 20250210.

I opened my exported Test .ics file, and changed the DTSTART and DTEND dates to one year ahead, and one day back: to 20260209. I reimported it to my next year's version of my Google Calendar for this paper. And it worked perfectly.

However, now I have 48 appointments to change with variable dates, in variable formats. That will be an Excel formula job which I will begin to tinker with in Part 2 (and maybe part 3 if it gets too complicated - we will see) :-)


Sam

References:

GCal Tools. (2020, November 12). How to undo an import to Google Calendar [video]. YouTube. https://youtu.be/hJdGBmHDafA

Google Calendar Help. (2025, January 1). Copy Google Calendar Events from 2024 Calendar year to 2025. https://support.google.com/calendar/thread/319764201/copy-google-calendar-events-from-2024-calendar-year-to-2025-year?msgid=320864848#

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