Can I give the events a time zone?

Write the instant in UTC with a trailing Z — 2026-09-07T12:00:00Z — and every calendar will show it at the right local hour for whoever is looking. A CSV has no column for a named zone, so that is the way to be unambiguous from a spreadsheet. If the wall-clock time is what must stay fixed across a daylight-saving change, build the file and then edit the DTSTART lines, or keep the calendar in .ics from the start.

What if I leave the end column empty?

The event is written with a start and no end, which most calendars display as a short block of their own default length. It is fine for a deadline or a reminder and unhelpful for a lecture. If your sheet has a duration rather than an end time, add an end column and compute it once with a formula — a spreadsheet does that better than any converter could.

Can other people subscribe to the file I made?

Only if you publish it somewhere with a stable address, because subscribing means fetching a URL periodically. A file you email is imported once and then diverges from your sheet the moment you edit a row. For a schedule that will change, publish the .ics at a fixed address and rebuild it there when the sheet changes — the subscribers then follow along without another import.

Building a Calendar From a Schedule You Already Have in a Spreadsheet

Published 9/10/2026 · 4 min read · File tools

Daniel Okonkwo — Front-end developer and tech writer at OneKitly

Web performance · File formats

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In short

The importer needs a header row and at least one of four columns: a title, a start, an end and a location — in English or in any of French, Spanish, Portuguese, German or Italian, so titre, début, fin, lieu works as well as summary, start, end, location. Write the dates the unambiguous way, year first: 2026-09-07 for a whole day, 2026-09-07T14:00:00Z for a moment. Everything else is optional, and columns the tool does not recognise are ignored rather than guessed at, so the reference numbers and the room capacities in your sheet cost nothing. What comes out is a list of separate events, one per row, with no recurrence rules attached — which is exactly right for a programme of one-off sessions and the wrong way to store a standing weekly meeting. Load the result in the .ics viewer and check one row before importing a hundred; a date that a spreadsheet quietly reformatted is the failure you are looking for.

Course timetables, match fixtures, shift rotas and conference programmes all start life as a table. Four columns are enough to turn one into a file every calendar application can import.

One row, one event — and why that is usually what you want

A term's teaching, a season's fixtures and a festival's programme are all lists of individual occasions that happen to fall into a pattern. Written out as rows they can be edited one at a time, which is what actually happens: one lecture moves to a different room, one match is postponed, one talk is cancelled. A recurrence rule would compress them and then fight you every time reality diverged from the pattern, which it does within the first fortnight.

The date column is where this goes wrong

Every other column is text and survives untouched. Dates are the one thing a spreadsheet believes it understands, so it reformats them to the convention of whoever opened the file — and 07/09/2026 is the seventh of September in most of the world and the ninth of July in the United States. The file will convert cleanly either way; it is the meaning that changed. Writing year-month-day removes the ambiguity at the source and is also what sorts correctly as text, which is a second reason to prefer it.

CSV to ICSTurn a spreadsheet of dates into a calendar file any app can subscribe to.Try the tool →

Frequently asked questions

Can I give the events a time zone?: Write the instant in UTC with a trailing Z — 2026-09-07T12:00:00Z — and every calendar will show it at the right local hour for whoever is looking. A CSV has no column for a named zone, so that is the way to be unambiguous from a spreadsheet. If the wall-clock time is what must stay fixed across a daylight-saving change, build the file and then edit the DTSTART lines, or keep the calendar in .ics from the start.
What if I leave the end column empty?: The event is written with a start and no end, which most calendars display as a short block of their own default length. It is fine for a deadline or a reminder and unhelpful for a lecture. If your sheet has a duration rather than an end time, add an end column and compute it once with a formula — a spreadsheet does that better than any converter could.
Can other people subscribe to the file I made?: Only if you publish it somewhere with a stable address, because subscribing means fetching a URL periodically. A file you email is imported once and then diverges from your sheet the moment you edit a row. For a schedule that will change, publish the .ics at a fixed address and rebuild it there when the sheet changes — the subscribers then follow along without another import.

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All guides →

ExplainerA Recurring Event Is One Line in the CSV, Not TwelveAn .ics file stores a weekly meeting once, with a rule attached. Export it to CSV and you get a single row for the whole series — which is the file being honest, not the converter losing rows.ExplainerThe Same .ics File Can Mean Five Different TimesiCalendar writes a start time in one of three ways, and only one of them is unambiguous. A meeting written with a named zone, converted on machines in Paris, New York and Honolulu, spanned nineteen hours and changed day.How-toYou Do Not Have to Rename Your Columns to EnglishThe header row is matched in six languages, so prénom, apellidos, Vorname and cognome are all understood. One header is genuinely ambiguous — nom — and it is settled by the column next to it.ComparisonThe JSON Export Keeps Three Things the CSV Has No Column ForSame file, same parser, two outputs. The spreadsheet gets eight columns; the JSON gets the named time zone, the all-day flag and the recurrence rule as well.How-toMerging Calendars and Address Books Appends — It Does Not DeduplicateThe merge tools put every record from every file into one output, in the order you gave them. That is the right default and the one thing to know before you feed in two exports of the same account.ExplainerA vCard Address Has Seven Parts, and a CSV Column Has OneNames, addresses and organisations are structured fields in a vCard. Flatten them into a spreadsheet and they read identically while losing the seams — which matters the moment you build a vCard back out of that spreadsheet.

Sources

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