Step 1 / source
Choose the source
Drop one file here
Choose the event xlsx worksheet you want to turn into importable ics calendar.
Checking publication status...LOCAL CALENDAR CONVERTER / EXCEL TO ICS
Excel to ICS
Convert a strict event worksheet into an importable ICS calendar with explicit all-day and UTC date rules.
Processed in this browserOne unencrypted .xlsx file up to 15 MB and 50 worksheets. The selected sheet supports one header row plus up to 1,000 events; every row needs title and start.
XLSX - 1,000 events
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 unencrypted .xlsx file up to 15 MB and 50 worksheets. The selected sheet supports one header row plus up to 1,000 events; every row needs title and start.
Plain-language method
How Excel to ICS works
Nirmion reads stored worksheet values, maps title, start, end, location, and description headers, validates each event, generates stable local UIDs, escapes and folds ICS lines, and writes one VCALENDAR containing one VEVENT per accepted row.
- 01Choose a valid source
Use title and start headers. Optional headers are end, location, and description. Dates must be YYYY-MM-DD or UTC YYYY-MM-DDTHH:MM:SSZ text.
- 02Review the conversion choices
Worksheet number follows tab order, including hidden sheets. The calendar name is escaped safely for the ICS header.
- 03Inspect the separate result
The result ends in _nirmion_tools_calendar.ics. Test it in a secondary calendar before importing into an important account.
Useful when
Practical jobs this tool handles
- Import an approved event plan into calendar software.
- Create a campaign calendar from a worksheet.
- Generate deterministic calendar fixtures.
Before converting
Check the source and destination rules
- Verify title and start headers.
- Keep start and end in the same date style.
- Test a small import and check time zones before a full rollout.
Know the boundary
Know what the destination format cannot keep
The converter does not infer local time zones, recurrence, attendees, alarms, or meeting links. All-day dates and UTC timestamps are the only accepted date contracts.
Quick answers
Questions before you convert
The conversion contract is deliberately explicit.
Can I use regional date formats?
No. Explicit ISO-style dates avoid day-month ambiguity.
Are formulas recalculated?
No. Use stored text values in the required date form.
Will importing create duplicates?
Repeated imports may create repeated events depending on the calendar provider, so test first.