# How often are my calendars updated?

> [!INFO]
> It is important to understand that the iCal sync is automatic, but not immediate. And that it is a 2-way sync, but each “way” is run independently by each platform. You may want to first check our following article: [How does the iCal synchronization work?](https://documentation.maestrel.com/31129603?source=issue-view)

Each platform updates their calendars at their own frequency. It is therefore normal that after 5 minutes, it is not updated. It usually can take 1-2h to update, and HBook does not have any control over the sync frequency of the external platforms.

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### Updating iCal calendars from HBook

There are two different aspects to keep in mind:

- What you can set is at which frequency HBook updates its calendar (i.e. HBook checks your external platforms' calendars and imports any new reservations), and that can be done in **HBook > iCal sync > Import settings**. But this has no impact on the frequency at which the external platforms update their calendars.
- The action “Update calendars” in **HBook > iCal sync** will only force HBook to check your external platforms' calendars to import/update HBook calendars accordingly (let’s say you have received a new reservation on AirBnb, HBook will block the dates and import the reservation).

However, it is important as well to have in mind that your servers and the external platforms' servers have rules in place to prevent too frequent calls to the server. It can explain that sometimes you will click to update manually, but it will not. Let’s say you click several times in a row, even if you will not see a message other than one informing you that it has updated, it will clearly have been blocked for security purposes.

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### Behaviours to watch out for

Now, what is not the normal behaviour is if a change in HBook is not reflected automatically after various hours. The update frequency is usually between every hour and every 4 hours, depending on the platform.

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#### Information regarding frequency update by platform

We list below available information specific to each platform.

- **AirBnb**: It may take up to 3h [according to their documentation](https://www.airbnb.com/help/article/99) (but customer feedback indicates a more frequent sync, usually every 1h30-2h).
- [**Booking.com**](http://Booking.com) **:** They indicate [on their documentation](https://partner.booking.com/en-gb/help/rates-availability/extranet-calendar/how-synchronise-your-calendars-across-channels) that it updates every 2h, but from our customers' feedback, it is very different depending on the regional area. We have customers who experience very good sync frequency (every 1h-1h30) and others for whom it is more every 3-4h.
- **Google Calendar** : There are known issues with Google Calendar, with irregular update frequency. This is not specific to HBook and is an ongoing issue that Google has not fixed for years.