How add-to-calendar links work
Google Calendar, Outlook and Yahoo each accept a web link with the event's details inside it. Clicking it opens the person's calendar with a new event ready to save. Nothing to install, and no account with you needed.
Apple Calendar has no link like that, so it uses an .ics file instead: a small text file in the iCalendar format that almost every calendar app can open, including Apple Calendar and the Outlook desktop app.
Getting time zones right
The links store times in UTC, written like 20261210T230000Z, where the Z means UTC. That one is 6 pm on 10 December in New York. Each guest's calendar converts it to their own time, so someone in London sees 11 pm.
So enter times in the event's own time zone, where it happens or where the host is for online events, and the conversion takes care of everyone else. Daylight saving is handled too, because you pick a city rather than a fixed offset.
All-day and multi-day events
All-day events have no times or time zones; they sit on the same date everywhere. Calendars store the end as the day after the last day, so a one-day event on 10 December ends on 11 December. This tool adds that day for you, so just enter the last day of the event.
Frequently asked questions
How do I make a Google Calendar link?
Start with https://calendar.google.com/calendar/render?action=TEMPLATE and add text, dates, details and location. Dates are UTC start and end, like 20261210T230000Z/20261211T000000Z. This tool builds it for you.
How do I add an event to Apple Calendar?
Download the .ics file and open it on a Mac, iPhone or iPad. Calendar asks which calendar to add the event to.
What's the difference between the Outlook.com and Office 365 links?
Outlook.com is for personal Microsoft accounts, like outlook.com and hotmail.com addresses. Office 365 is for work and school accounts. They open different sites, so pick the one your guests use.
Why does my event show at the wrong time?
The time zone is probably wrong. Set it to where the event happens, or where the host is for online events, rather than to UTC.
Do these links send an invite?
No. They add the event to the guest's own calendar, but don't notify you or collect RSVPs. For those, send an invite from your calendar or use an event platform.