RFC 5545 Calendar File Utility
Need Email URLs? Add-to-Calendar Link Generator →ICS File Generator
Create a standards-compliant .ics calendar file for a meeting, contractual deadline, appointment, or single work shift. Preview the event structure in real time, download the file locally, and import it into Google Calendar, Microsoft Outlook, or Apple Calendar.
.ics files. To generate a full year of repeating rotations or payroll dates at once, use our
Shift Calendar Generator
or
2026 Biweekly Pay Period Calendar
.
Configure event
Enter the details you want calendar apps to import.
1. Importing Your .ICS File Across Platforms
Every major desktop and mobile calendar application supports the iCalendar (text/calendar) file format natively. Download the generated .ics file first, then follow your client's import workflow.
Google Calendar
On desktop web, open Settings → Import & export, choose your .ics file, and pick a destination calendar.
Microsoft Outlook
In Outlook Web or New Outlook, go to Add calendar → Upload from file. In Classic Outlook, use File → Open & Export.
Outlook Import Guide →Apple Calendar
Double-click the file on macOS or download via Safari on iPhone/iPad to open the native iCloud event sheet.
iPhone Calendar Guide →2. Technical Anatomy of an RFC 5545 .ICS File
Under IETF RFC 5545, an iCalendar file is a UTF-8 plain-text container delimited by BEGIN:VCALENDAR and END:VCALENDAR lines using CRLF (\r\n) line endings. Inside that envelope sits one or more VEVENT blocks. Missing a required property—such as VERSION:2.0, PRODID, UID, or DTSTAMP—is the primary reason strict parsers like Google Calendar and Exchange reject hand-crafted files. For deep-dive parser diagnostics, read our
ICS File Format & RFC 5545 Troubleshooting Guide
.
| Property | Scope | RFC 5545 Role & Parser Requirement |
|---|---|---|
| VCALENDAR | Root | Outer container declaring VERSION:2.0 and PRODID generator metadata. |
| VEVENT | Component | Encapsulates a single scheduled calendar entry, milestone, or shift block. |
| UID | Required | Globally unique string used for deduplication and in-place event updates across re-imports. |
| DTSTAMP | Required | UTC timestamp (YYYYMMDDTHHMMSSZ) recording when the iCalendar object was created. |
| DTSTART / DTEND | Timing | Defines start and non-inclusive end boundaries via UTC (Z), local TZID, or VALUE=DATE. |
| SUMMARY / LOCATION | Metadata | Event title, physical address or video link, and escaped plain-text DESCRIPTION notes. |
Minimal Valid RFC 5545 Wire Structure
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//WCalendar//ICS Generator//EN
CALSCALE:GREGORIAN
BEGIN:VEVENT
UID:[email protected]
DTSTAMP:20261103T120000Z
DTSTART:20261112T150000Z
DTEND:20261112T160000Z
SUMMARY:Q4 Operations & Payroll Cutoff Review
LOCATION:Conference Room B / Video Bridge
DESCRIPTION:Finalize holiday ACH submission windows before Thanksgiving.
END:VEVENT
END:VCALENDAR
3. Timezone Formats (Z vs. TZID vs. VALUE=DATE) & Common DST Pitfalls
Calendar bugs almost always stem from choosing the wrong DTSTART/DTEND timestamp mode for the event type:
| Timestamp Mode | Syntax Example | How Calendar Apps Interpret It | Common Pitfall to Avoid |
|---|---|---|---|
| UTC Absolute Time | DTSTART:20261112T150000Z | Locks the event to an exact instant in Coordinated Universal Time; converts automatically to each attendee's local timezone. | Calculating the UTC offset using standard time for a summer Daylight Saving date shifts the meeting by 1 hour. |
Zoned Wall-Clock (TZID) | DTSTART;TZID=America/New_York:20261112T100000 | Pins the event to a named IANA region (e.g., 10:00 AM Eastern) and respects regional DST transitions. | Classic desktop Outlook may misread TZID if the file omits a matching VTIMEZONE definition block or uses non-IANA names. |
All-Day Date (VALUE=DATE) | DTSTART;VALUE=DATE:20261112 | Renders as a banner at the top of the calendar day regardless of which timezone the user travels to. | DTEND is exclusive (20261113 for a 1-day Nov 12 event). Never use T000000Z for all-day holidays or shifts. |
| Floating Local Time | DTSTART:20261112T090000 | Appears at 9:00 AM in whatever local timezone the importing user's calendar is currently set to. | Dangerous for live video calls across timezones—a London and Chicago attendee would join 6 hours apart! |
4. Best Practices for Distributing Corporate .ICS Event Files
Omit METHOD:REQUEST on Downloads
Downloadable website and email attachment .ics files should omit METHOD:REQUEST (or use METHOD:PUBLISH). Including METHOD:REQUEST without matching ORGANIZER/ATTENDEE headers causes Outlook and Google Calendar to reject self-imports.
Preserve Stable UID Values
If you reschedule a corporate town hall or filing deadline, re-issuing an .ics with the original UID and an incremented SEQUENCE:1 updates the existing calendar slot instead of stranding a duplicate entry at the old time.
Pair .ICS with Web Compose Links
On mobile Android and Gmail webmail, clicking an .ics file requires downloading and opening a file attachment. Pair your file with direct Google and Microsoft 365 URLs from our
Add to Calendar Link Generator
for one-tap mobile conversion.