{{ result.summaryTitle }}
{{ result.primary }}
{{ result.summaryLine }}
{{ badge.label }}
Use the calendar-facing name attendees should see.
{{ fieldErrors.title }}
Pick the event start date.
{{ fieldErrors.start_date }}
Use 24-hour local time for the selected timezone.
{{ fieldErrors.start_time }}
Use the same timezone the calendar event should honor.
Set the meeting length in minutes.
min
{{ fieldErrors.duration_minutes }}
Add a room, address, or video link.
Agenda, dial-in notes, owner context, or attendee prep.
Writes date-only DTSTART/DTEND fields for events without a start time.
Use 1 for a single all-day event.
day(s)
{{ fieldErrors.duration_days }}
Leave off when the importing calendar should choose its own reminders.
Most standalone invitations use Confirmed.
Use Busy for meetings and Free for FYI holds.
Optional. Use a valid email address, or leave blank.
{{ fieldErrors.organizer_email }}
{{ result.icsText || result.icsPlaceholder }}
Field Value Calendar note Copy
{{ row.field }} {{ row.value }} {{ row.note }}
Check Status Detail Copy
{{ row.check }} {{ row.status }} {{ row.detail }} 
{{ jsonPayloadText }}
Tags: Date Time, Productivity
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An iCalendar file is a small text file that tells calendar apps how to add an event. The file usually has a .ics extension and stores the event title, start, end, location, notes, availability, and other fields in a standard format. People use it when a date needs to move from a form, document, ticket, or workflow into Apple Calendar, Google Calendar, Outlook, or another calendar client without retyping every detail.

The important part is not only the date. Calendar imports need to know whether a time is an exact UTC timestamp, a named timezone time, a floating local time, or a date-only all-day entry. A meeting at 14:30 in Kuala Lumpur and a floating 14:30 event can look similar in a preview, but they can land differently for someone importing the file in another region.

All-day entries have their own calendar rule. The end date is exclusive, so a one-day all-day event starts on the shown date and ends at the start of the next date. That can feel odd when reading raw DTEND text, but it is the convention that lets multi-day events span complete dates without adding a hidden end time.

An ICS file is a portable event record, not a full scheduling conversation. It can carry a publishable event and a display reminder, but it does not replace attendee replies, room booking rules, recurrence management, or a calendar server that tracks later edits.

Technical Details

The iCalendar format is built from content lines. Each line has a property name, optional parameters, a colon, and a value. A basic event sits inside BEGIN:VEVENT and END:VEVENT, while the outer BEGIN:VCALENDAR block declares the calendar object, version, product identifier, scale, and method.

Event timing is expressed with DTSTART and DTEND. The start is inclusive and the end is exclusive. Timed entries use a date-time value such as 20260520T143000, while all-day entries use a date value such as 20260520. For an all-day event, the exclusive end date is one day after a one-day event, two days after a two-day event, and so on.

Date-time values can be written in three useful ways. A floating local time omits both Z and TZID, so the importing calendar reads the same clock time in its own context. A UTC time ends with Z. A named timezone time writes a TZID parameter next to DTSTART and DTEND. This generator writes common timezone names directly, but it does not add a full VTIMEZONE definition, so strict calendar systems may interpret named zones differently than mainstream calendar clients.

ICS field How it is filled Why it matters
SUMMARY The event title, up to 160 characters The main name shown by the calendar app.
DTSTART Start date plus either date-only mode, floating time, UTC, or selected TZID Places the event on the calendar.
DTEND Timed start plus minute duration, or all-day start plus day count Sets the exclusive endpoint used by calendar clients.
LOCATION Optional room, address, or meeting link Gives the importing user a place to attend or join.
DESCRIPTION Optional notes with ICS-safe escaping for newlines, commas, semicolons, and backslashes Keeps agenda notes readable after import.
STATUS and TRANSP Confirmed, tentative, or cancelled status, plus busy or open availability Helps compatible clients label the event and decide whether it blocks time.
VALARM Optional display reminder from 5 minutes to 1 day before start Adds a simple reminder block when the importing calendar honors it.
UID A stable identifier derived from title, timing, location, and organizer email Gives the event a consistent identity inside the file.
Mode Generated timing shape Best reading
Floating local time DTSTART:20260520T143000 The same local clock time is imported without binding the event to a zone.
UTC DTSTART:20260520T143000Z The event is anchored to an absolute timestamp.
Named timezone DTSTART;TZID=Asia/Kuala_Lumpur:20260520T143000 The event is written with a timezone identifier that compatible clients can resolve.
All-day event DTSTART;VALUE=DATE:20260520 The event uses date-only boundaries and ignores the time and timezone controls.

Text fields are escaped before they are written into the file. Backslashes become doubled, line breaks become \n, and commas or semicolons receive a leading backslash. Long content lines are folded with continuation lines so calendar clients can unfold the text back into the original value.

Input or option Accepted range Failure behavior
Title Required, up to 160 characters Export stays blocked until a title is present.
Start date Valid YYYY-MM-DD calendar date Invalid dates are flagged before ICS text is produced.
Start time Valid 24-hour HH:MM time when all-day mode is off Timed export waits for a valid clock value.
Timed duration 1 to 10,080 minutes Out-of-range durations are rejected.
All-day length 1 to 30 days The date-only end date is not generated until the length is valid.
Description Optional, up to 4,000 characters Long notes are kept inside the entered limit before escaping.
Organizer email Blank or a valid email-like address An invalid organizer blocks export until corrected or removed.

Everyday Use & Decision Guide

Start with the calendar entry someone should see after import. Put the real meeting name in Event title, then set the start date and either a timed start or All-day event. For ordinary meetings, leave the duration in minutes and pick the timezone that matches the event location. For date-only reminders, holidays, launches, travel days, or conference blocks, use all-day mode and set the day count instead.

Choose Floating local time only when the event should stay on the same wall-clock time for the importing person. A daily reminder at 09:00 can make sense that way. A team call, webinar, deadline, flight, or coordinated release usually needs UTC or a named timezone so different calendars do not silently shift the intended instant.

  • Use Reminder when the file should include a basic display alert. Leave it off when the destination calendar should apply its own reminder rules.
  • Set Status to Confirmed for normal imports, Tentative for holds, and Cancelled only when the imported event should visibly show cancellation state.
  • Use Availability as Busy for meetings that should block time. Use the open setting for FYI events or date markers that should not reserve the schedule.
  • Add Organizer email only when an owner address helps the imported record. It is not the same as sending invitations or collecting replies.
  • Check Calendar Checks before downloading. A Needs edit row means the ICS file is not ready to export.

The generated ICS text, JSON payload, field table, and check table are produced in the browser. Copy or download only after the preview filename, start and end values, timezone mode, and reminder badge match the event you intended to import.

Step-by-Step Guide

  1. Enter the event title that should appear as the calendar subject.
  2. Pick the start date. For timed events, add the start time and choose the timezone mode before setting the duration in minutes.
  3. For a date-only event, open Advanced, turn on All-day event, and set the all-day length in days.
  4. Add location and description details if the imported calendar entry needs a room, address, video link, agenda, dial-in note, or attendee prep text.
  5. Use the advanced reminder, status, availability, and organizer controls only when those fields should be written into the file.
  6. Review Event Fields to confirm SUMMARY, DTSTART, DTEND, timezone mode, STATUS, TRANSP, and UID.
  7. Open Calendar Checks and clear any Needs edit status before export.
  8. Use Copy ICS when another workflow needs the raw text, or Download .ics when you want to import a file into a calendar app.

Interpreting Results

The summary strip is the first trust check. ICS file ready means the required fields passed validation and the download button can produce a text/calendar file. The filename is based on the event title, and the summary line shows the interpreted start, end, and timezone mode. If the strip says the ICS needs input, fix the highlighted field before using the output.

Event Fields is the most useful audit view when a calendar import would be hard to undo. It shows each generated field, the value written, and a plain note about what that field means. Calendar Checks focuses on readiness: required fields, text escaping, line folding, timezone handling, reminder block, organizer email, and download readiness.

Result cue What it means What to check next
ICS file ready The event has enough valid information to copy or download. Review the start, end, timezone mode, and filename.
Fix n issue(s) At least one required field or validation bound failed. Use the red field message and Calendar Checks detail.
DTEND is the following date for all-day mode The end date is exclusive, not a visible extra day. Compare All-day length with the displayed end note.
Timezone check shows Info The file is using floating time or date-only all-day behavior. Confirm that this is intentional before sharing the file.
No VALARM is included The reminder selector is off. Leave it that way for destination-managed reminders, or choose a reminder before export.

The JSON tab is for review and handoff, not for importing into a calendar app. Calendar apps usually need the copied ICS text or the downloaded .ics file.

Worked Examples

Regional meeting with a named timezone

A launch review starts on 2026-05-20 at 14:30 in Asia/Kuala_Lumpur and runs for 45 minutes. The timing fields become DTSTART;TZID=Asia/Kuala_Lumpur:20260520T143000 and DTEND;TZID=Asia/Kuala_Lumpur:20260520T151500. The field table should show a 45 min duration and the timezone mode should name the same TZID.

Two-day all-day event

A two-day onsite workshop begins on 2026-06-10. Turning on All-day event and setting the length to 2 days writes DTSTART;VALUE=DATE:20260610 and DTEND;VALUE=DATE:20260612. The event covers June 10 and June 11. June 12 is the exclusive boundary where the all-day event stops.

Floating reminder for local routines

A personal weekly planning block at 09:00 can use floating local time when every importer should see it at 09:00 in their own calendar context. In that case the timing line has no Z suffix and no TZID parameter. That is useful for local routines, but it is risky for shared calls where everyone must meet at the same actual moment.

FAQ

Does the generated event leave the browser?

The event text, field table, check table, and JSON payload are generated in the browser. The data leaves your device only when you copy it, download it, import it into another app, or share the resulting file yourself.

Does this send invitations to attendees?

No. The file contains one publishable event record. It does not add attendees, send email, request replies, reserve rooms, or track later schedule changes.

Why does an all-day event end on the next date?

All-day DTEND is exclusive. A one-day event starting on May 20 ends at the start of May 21 in the raw file, even though the visible event covers only May 20.

Should I use floating time, UTC, or a named timezone?

Use floating time for same-clock local routines. Use UTC when you need an absolute timestamp. Use a named timezone when the event belongs to a region and the importing calendar is expected to understand that TZID.

Why is my organizer email rejected?

The organizer field must be blank or look like a valid email address. Remove spaces, add the missing domain, or leave the field empty if the imported event does not need an owner address.

Can I edit the ICS text after export?

Yes, but small syntax mistakes can break import. If you need to change title, time, location, notes, reminder, status, or availability, it is safer to edit the fields and generate the file again.

Glossary

ICS
A plain-text calendar file format commonly imported by calendar apps, usually saved with a .ics extension.
iCalendar
The standard calendar data format used to describe events, to-do items, journal entries, and availability data.
VEVENT
The event component inside an iCalendar file.
DTSTART
The inclusive event start date or date-time.
DTEND
The exclusive event end date or date-time.
Floating time
A date-time value with no UTC marker and no timezone identifier. It is read as the same local clock time by the importing calendar context.
TZID
A timezone identifier parameter attached to a date-time field.
VALARM
An optional alarm component, used here for a display reminder before the event start.

References