How to Create an ICS File
An ICS file is just structured text — you can write one in any text editor. Here's a working minimal template, the rules that actually matter, and the point at which you should stop hand-writing and use a converter instead.
A minimal, working ICS file
Copy this, change the values, save it as events.ics — it imports into every major calendar app:
BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//your-name//your-app//EN
BEGIN:VEVENT
UID:20260728-standup-1@example.com
DTSTAMP:20260724T120000Z
DTSTART;TZID=America/New_York:20260728T090000
DTEND;TZID=America/New_York:20260728T091500
SUMMARY:Team standup
LOCATION:Zoom
DESCRIPTION:Daily sync\nBring updates
END:VEVENT
END:VCALENDARTo hold more events, repeat the whole BEGIN:VEVENT … END:VEVENT block — one per event, each with its own unique UID — all inside the single VCALENDAR envelope.
The fields, line by line
| Line | Required | What it does |
|---|---|---|
| VERSION:2.0 | Yes | Declares the iCalendar spec version. Always exactly 2.0. |
| PRODID | Yes | Identifies the software that made the file. Any -//org//app//EN string. |
| UID | Yes | Globally unique event ID. Calendars use it to match updates to existing events — duplicated UIDs make events overwrite each other. |
| DTSTAMP | Yes | When this file was generated, always UTC (trailing Z). |
| DTSTART / DTEND | DTSTART yes | Start and end. With TZID=… for local times, trailing Z for UTC, or VALUE=DATE for all-day. No DTEND means zero duration (most apps render ~1 hour). |
| SUMMARY | No | The event title. |
| LOCATION / DESCRIPTION | No | Where, and free-form notes. Escape , ; \ and use \n for line breaks. |
| RRULE | No | Recurrence rule — see the examples below. |
Recurring events: RRULE recipes
Add one RRULE line inside the VEVENT. The pattern expands from DTSTART:
RRULE:FREQ=WEEKLY;BYDAY=MO,TU,WE,TH,FRRRULE:FREQ=WEEKLY;BYDAY=MO,WE,FR;COUNT=30RRULE:FREQ=MONTHLY;BYMONTHDAY=1RRULE:FREQ=MONTHLY;BYDAY=2TURRULE:FREQ=YEARLY;UNTIL=20281231T235959ZThis is the one thing spreadsheets can't express — CSV has no recurrence column — so the usual workflow is: generate single events from CSV with the converter, then paste an RRULE into the few events that repeat.
The rules that break hand-written files
- Escaping: inside text values, write commas as
\,semicolons as\;backslashes as\\and newlines as\n. - Line endings: the spec requires CRLF (\r\n). Most apps tolerate LF, but strict parsers exist — generated files should use CRLF.
- Line folding: lines longer than 75 bytes should wrap onto a next line that starts with a single space. Editors don't do this for you; it's the main reason long descriptions break hand-made files.
- Exclusive DTEND: all-day events end the day after the last day. Off-by-one imports are almost always this.
- Timezones: a bare TZID reference technically wants a matching VTIMEZONE block defining the zone's DST rules. Big apps substitute their own definitions, but embedding it (as our converter does) is what the spec asks for.
Sanity-check any hand-written file by dropping it into the ICS viewer — its tolerant parser lists warnings that point at broken lines — or round-trip it through the ICS to CSV converter to see every field as a table.
Creating ICS files — FAQ
What is an ICS file exactly?
A plain-text file in the iCalendar format (RFC 5545) — the universal interchange format for calendar data. It wraps one or more VEVENT blocks inside a VCALENDAR envelope, each holding properties like SUMMARY, DTSTART and LOCATION. Google Calendar, Outlook and Apple Calendar all read and write it.
Can I create an ICS file in Notepad or TextEdit?
Yes — it's just text. Copy the minimal template on this page, edit the values, and save with an .ics extension (in TextEdit, use Format → Make Plain Text first). The spec formally requires CRLF line endings; most calendar apps forgive plain LF, but files from this site's converter use proper CRLF so they work everywhere.
Which fields are required in a VEVENT?
Three: UID (a globally unique ID — any unique string plus an @domain suffix works), DTSTAMP (when the file was created, in UTC), and DTSTART (when the event begins). Everything else — SUMMARY, DTEND, LOCATION, DESCRIPTION, RRULE — is technically optional, though an event without a SUMMARY shows up untitled.
How do I make an all-day event in ICS?
Use DATE values instead of date-times: DTSTART;VALUE=DATE:20260803 with DTEND;VALUE=DATE:20260804. Watch the trap — DTEND is exclusive, so a one-day event on Aug 3 ends on Aug 4, and a conference running Aug 10-12 needs DTEND of Aug 13.
How do I make a recurring event in ICS?
Add an RRULE line to the VEVENT. Examples: RRULE:FREQ=WEEKLY;BYDAY=MO,WE,FR for Mon/Wed/Fri; RRULE:FREQ=MONTHLY;BYMONTHDAY=1 for the 1st of each month; append COUNT=10 or UNTIL=20261231T000000Z to stop it. The recurrence expands from your DTSTART, so make sure the first occurrence matches the rule.
Why won't my hand-written ICS file import?
The usual suspects, in order: a missing or duplicated UID, special characters not escaped (commas, semicolons and backslashes must be written \, \; and \\, newlines as \n), a DTEND earlier than DTSTART, mismatched BEGIN/END pairs, or the file saved with rich-text formatting. Drop the file into our ICS viewer — it reads tolerantly and its warnings usually point straight at the broken line.
Is there a faster way than writing ICS by hand?
For more than a couple of events, yes: put them in a spreadsheet with Subject / Start Date / Start Time columns and run it through our CSV to ICS converter. It generates the UIDs, escaping, folding, CRLF endings and timezone definitions automatically, with a preview before download — and it all runs in your browser.