LOCAL CALENDAR CONVERTER / CSV TO ICS

ICS Calendar Generator

Turn a strict event CSV into an importable ICS calendar with all-day dates or explicit UTC start and end times.

Processed in this browserOne UTF-8 CSV up to 2 MB and 1,000 events. Required headers are title and start; timed events require end. Values use YYYY-MM-DD or ISO UTC timestamps ending in Z.

Step 1 / source

Choose the source

CSV - 1,000 events

Drop one file here

Choose a reviewed event table that follows the documented title, start, end, location, and description columns.

Browse filesChecking publication status...

No file upload

This operation runs with browser APIs. Nirmion receives catalogue requests, not the selected source bytes.

Original stays unchanged

The converter creates a separately named output. It never writes back into the source file.

Bounded work

One UTF-8 CSV up to 2 MB and 1,000 events. Required headers are title and start; timed events require end. Values use YYYY-MM-DD or ISO UTC timestamps ending in Z.

Plain-language method

How rows become calendar events

Nirmion maps title or summary, start, optional end, location, and description headers into escaped VEVENT records. It writes CRLF lines, folds long content, adds UTC generation timestamps, and rejects mixed or reversed time ranges.

01
Choose a valid source
Use title,start,end,location,description headers. Dates use YYYY-MM-DD. Timed values use forms such as 2026-09-15T09:30:00Z; local times without a timezone are rejected.
02
Review the conversion choices
Choose comma, semicolon, tab, or pipe to match the file. Calendar name labels the collection but does not alter event titles.
03
Inspect the separate result
The UTF-8 .ics can be imported into many calendar applications. Review the imported event count, dates, timezone display, and duplicates before saving.

Useful when

Practical jobs this tool handles

Prepare a campaign or webinar schedule for import.
Convert an approved event spreadsheet export into a calendar.
Create a portable all-day deadline calendar.

Before converting

Prevent calendar surprises

Test a small calendar import before using all rows.
Use UTC timestamps ending in Z for timed events.
Back up or import into a temporary calendar to check duplicates.

Know the boundary

Date-only end values are exclusive

An all-day row without end becomes one day. When end is supplied for an all-day event, ICS treats it as the first date not included. Timed events require a later UTC end.

Quick answers

Questions before you convert

Strict input prevents ambiguous calendar times.

Can I use local time such as 09:30?

No. Timed values must include a full date and end in Z so the instant is unambiguous.

Is end required for all-day events?

No. A missing end creates a one-day event; a supplied date-only end is exclusive.

Will importing twice create duplicates?

Many calendar apps use event UIDs to identify records, but import behavior varies. Always test duplicates in the target application.