> ## Documentation Index
> Fetch the complete documentation index at: https://cal.id/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Extended Timezone Availability
> Assign timezones to individual availability slots in Cal ID so bookers only see the hours you set aside for their region.
Extended Timezone gives you per-slot control over global scheduling. Instead of one timezone governing your whole day, you decide which timezones can see and book each individual slot. A client can only book a slot if their timezone is one you assigned to it.
## How it works
When someone opens your booking link, Cal ID matches slots to the visitor:
1. **Location detection** — Cal ID reads the visitor's timezone from their browser or location as soon as the booking page loads.
2. **Rule matching** — Cal ID checks the timezone rules you set on each slot.
3. **Filtering** — if the visitor's timezone matches a slot's assigned timezones, they see that slot converted to their local time. If it does not match, the slot is hidden and you appear unavailable during those hours.
## Set it up
Break the day into separate windows if you want to offer different hours to different regions. Click the **plus (+) icon** next to the time inputs to add another slot to a day.
Next to a time slot, click the **globe icon** to open the timezone dropdown.
Select the timezones you want to target for that slot. Pick several to cover a whole region — multiple US or European zones, for example.
Click the blue **Save** button in the top-right corner to push the changes live.
Assign timezones slot by slot rather than day by day. A single weekday can carry one window for a domestic audience and another for an overseas one.
## Example: split local and international hours
Your Monday availability runs from 10:00 AM to 11:00 PM locally, but you want domestic and international clients in different windows.
| Slot | Local hours | Timezones assigned |
| ------ | ------------------ | --------------------------------------- |
| Slot 1 | 10:00 AM – 7:00 PM | Asia/Kolkata |
| Slot 2 | 7:00 PM – 11:00 PM | America/New\_York, America/Los\_Angeles |
A client in Mumbai only sees 10:00 AM–7:00 PM. A client in New York opening the same link only sees the evening options.
## Example: target regions through the day
You are a London consultant who takes European clients in the morning and Australian partners in the afternoon.
| Slot | Local hours | Timezones assigned |
| ------ | ------------------ | ------------------------------------- |
| Slot 1 | 8:00 AM – 12:00 PM | Europe/London, Europe/Berlin |
| Slot 2 | 1:00 PM – 5:00 PM | Australia/Sydney, Australia/Melbourne |
Each client group is sectioned off automatically, with no cross-booking between them.
## Why use extended timezones
* **No timezone math.** You stop converting hours before sending a link — Cal ID filters slots by the booker's timezone.
* **Protected working hours.** Each international market reaches you only during the window you chose for it.
## Related timezone and schedule settings
Build the schedule that these timezone rules sit on top of.
Keep separate schedules and attach the right one to each event type.
Change or block your hours on specific dates.
Set the account timezone your schedules are written against.
## Related topics
- [Create Availability in Cal ID](/docs/availability/create.md)
- [Multiple Schedules](/docs/availability/multiple-schedules.md)
- [Date Overrides or Set Unavailable](/docs/availability/date-overrides.md)
- [Configure Language, Timezone, and Travel Schedule in Cal ID](/docs/settings/general.md)