Dummy ICS File Generator
Every dummy ICS file is a valid iCalendar file with the number of events you choose, exact to the byte.
Sample ICS files, ready to download:
One click, exact size (1 KB = 1,024 bytes), default options, built in your browser.
A dummy ICS file is a valid iCalendar (.ics) file made for testing, with as many events as you choose. Download one free at the exact size you need, from 512 Bytes to 50 MB, with 1 to 10,000 events (10 by default). Each event is one hour long, one per day from 5 January 2026, with its own ID, so a calendar import should show exactly the number you set. It follows RFC 5545: CRLF line endings and no line longer than 75 characters.
How we check it: every generated file must be exactly the size you set and pass our own RFC 5545 checks (CRLF, 75-octet lines, event count, UID, DTSTART before DTEND) and the ical.js parser; the last run on 13 November 2026 passed 223 of 223 runs across 22 formats (how the files are made and checked).
What is inside a dummy ICS file
Plain text you can open in any editor (how we build and check these files):
- One VCALENDAR with VERSION 2.0, a PRODID, a calendar name and a description.
- The number of VEVENTs you set, each with a UID, DTSTAMP, start and end in UTC, a summary ("Dummy event 1"), a description, a location and a status.
- Extra size as X-DUMMY-PADDING lines placed before the events. Calendar apps ignore unknown X- properties.
- ASCII only, CRLF line endings, every line at most 75 characters, so no line folding is needed.
What a dummy ICS file is used for
Calendar imports
Import into Google Calendar, Outlook or your own app and check that the event count, dates and times come through.
Large feeds
A 10,000-event file shows how a calendar handles a big subscription feed or a slow parser.
Upload limits
Test the size limit of an .ics upload or attachment with a file that is a real calendar.
Parser tests
Unit-test an iCalendar parser with files of known content and size.
Testing a calendar import
Set the Number of events option and import the file. The first event starts on 5 January 2026 at 09:00 UTC and each one follows a day later, so 10 events run to 14 January. Check the count, the first and last date, and the time zone: all times are in UTC (the Z suffix), so a calendar in another zone should show them shifted.
Every UID is unique ("dummy-event-000001@dummyfiles.com" and so on). Importing the same file twice should update events rather than duplicate them, which is a handy test of how your app handles UIDs.
| Limit | Size | Notes |
|---|---|---|
| nginx client_max_body_size (default) | 1 MB 1,048,576 B | Requests with a larger body get HTTP 413. |
| PHP upload_max_filesize (default) | 2 MB 2,097,152 B | Also capped by post_max_size, so raise both. |
| AWS Lambda synchronous invocation payload | 6 MB 6,291,456 B | Applies to request and response. |
| Amazon API Gateway REST API payload | 10 MB 10,485,760 B | Hard quota for REST APIs. |
| Outlook default attachment limit (Exchange accounts) | 10 MB 10,485,760 B | Administrators can change it. |
| Outlook attachment limit (internet accounts) | 20 MB 20,971,520 B | Per Microsoft Outlook guidance. |
| Gmail message size limit | 25 MB 26,214,400 B | Attachments grow about a third when encoded, so a 20 MB file can already be too big. |
ICS file details
- Extension
- ICS .ics
- MIME type
- text/calendar
- Smallest size
- 512 Bytes
- Largest size
- 50 MB
- Contents
- iCalendar (RFC 5545) with the number of one-hour events you choose (10 by default), CRLF lines of at most 75 octets
Dummy ICS file FAQ
Is the dummy ICS file valid?
Yes. It follows RFC 5545, and we check every generated file with our own rules and with the ical.js parser from Mozilla.
How many events does the dummy ICS file have?
10 by default. Set the Number of events option to anything from 1 to 10,000. The file stays exactly the size you set.
What dates do the events use?
One-hour events, one per day, from 5 January 2026 at 09:00 UTC. All times are in UTC, so your calendar converts them to your time zone.
How is the exact file size reached?
Extra bytes go into X-DUMMY-PADDING lines before the events. Calendar apps ignore unknown X- properties, so the events are the same at any size.
What is the smallest dummy ICS file?
About 3 KB for the default 10 events, and 512 Bytes at the very least. If the size is too small for the number of events, the tool says the minimum.
What is the MIME type of an ICS file?
text/calendar. Servers that send .ics files should use it, so that browsers hand the file to a calendar app.
Is my calendar uploaded?
No. The file is built in your browser and never sent to a server.