All-day events: when a date should stay a date
Learn when to use an all-day calendar entry and when a precise time and time zone are essential.
A birthday is different from a broadcast
A birthday or a local holiday usually identifies a calendar date, not one simultaneous instant around the world. An all-day entry communicates that distinction. The iCalendar standard has a date-only value as well as a date-and-time value. Do not turn every date into midnight UTC: that instant can still fall on the previous evening elsewhere. A reminder attached to a date is a separate choice about when you want to be notified.
Give deadlines an actual closing time
A registration deadline needs more detail than an all-day box marked Friday. State the date, closing time and organizing city or time zone. A deadline at midnight in Tokyo does not mean midnight in Paris. Use the time converter for the chosen date and include the resulting date as well as the hour when sharing it. Specify whether midnight opens the stated date or closes the previous one; a plain-language explanation prevents a costly misunderstanding.
Check the entry after sharing it
Calendar programs can display date-only entries and reminders differently when settings or travel locations change. Inspect what the recipient sees before relying on an important shared calendar. For a live event, keep a timed entry tied to the organizer's zone; for a birthday, preserve the intended date rather than inventing a global start time. Our guide to publishing international event times explains how to accompany an invitation with a clear public schedule.
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Related reading
UTC and local time: a practical explanation
Learn what an offset tells you, what it leaves out and how to write an unambiguous time.
How to publish an event time for an international audience
Make the date, location and intended instant clear wherever your invitation is read.