Convert 09:00 at +09:00 to UTC
Input and settings
2028-02-29 09:00–10:00 / +09:00
Expected result
DTSTART:20280229T000000Z / DTEND:20280229T010000Z. Comma/semicolon in the title are escaped.
Single Event ICS Generator
Create a timed or all-day event as a local ICS file. Set title, location and description without adding or sending it to a calendar.
How to use
- Enter the event title, start and end.
- Choose all-day or timed; for a timed event, check the fixed UTC offset.
- Create and save the ICS, then import it into a calendar and check the dates and times.
Event details
Title up to 200, location 1,000 and description 10,000 UTF-16 units. Input and results stay on this device.
Preview and save
How to use and supported formats
Enter title, location, description, start and end. Timed events convert a fixed UTC offset to UTC. All-day events include the selected end date; ICS DTEND is the next date. Supported years: 1900–9998.
Fixed offsets do not adjust for daylight saving time. Check the local offset for your event. Japan normally uses +09:00; UTC uses +00:00. Recurrence, reminders, attendees, invitations and calendar registration are unsupported.
UTF-8 ICS uses CRLF with lines folded within 75 bytes. Each creation generates a new UID, so importing repeated exports may create duplicates. Check dates and times in your calendar app before importing. Input and results are neither stored nor sent.
Try a use case and check the result
Inspect the ICS data for fixed-offset timed and all-day events.
Example buttons replace the inputs and settings above and calculate. Restore previous input steps back one example at a time. After trying multiple examples, repeat restore to return to your original input. This history is lost when the page closes.
An all-day event only on leap day
Input and settings
All day / Start and end both 2028-02-29 / Offset ignored
Expected result
DTSTART;VALUE=DATE:20280229 / DTEND;VALUE=DATE:20280301. The exclusive end is the next day.
How to read the result
All-day UI dates are inclusive; ICS DTEND is the following exclusive date. Timed events use the supplied offset to produce UTC. UID and creation time vary per generation, so whole-file fixed-string equality is inappropriate.
Scope and limits
Dates: 1900–9998. Timed end must follow start; all-day may use the same date. Fixed offsets within ±14:00 do not resolve regional daylight saving rules. No recurrence, invitations or reminders; import the saved ICS in your calendar. Examples/Undo terminate pending workers and discard late replies.
Independently verify leap day and UTC conversion, escaping, CRLF and saved data. Check date/datetime input types, original values and late worker replies.
Continue with the next task
Frequently asked questions
Is it added to my calendar?
No. This only downloads an ICS file.
Is the all-day end date included?
Yes. The exported ICS records the next date as its exclusive end.
Does it automatically resolve regional daylight saving time?
Timed events use the supplied fixed UTC offset. Regional daylight saving rules are not resolved; verify the offset for the event date.
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Inputs and storage
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