What Is iCal? How iCal Calendar Sync Works

Adriaan de Jager•Mar 2, 2026•Last modified November 11, 2026•8 min read

TL;DR

iCal is the calendar format (.ics) that booking platforms use to share availability with each other. An iCal sync keeps Airbnb, Vrbo, Booking.com and your own website on the same schedule, so a booked date blocks off on the other platforms too, without you touching anything.

• An iCal link exports your calendar. You import other platforms' links to see their bookings.

• Sync prevents double bookings and saves you from updating each site by hand.

• iCal shares availability only, and it isn't instant: Vrbo checks a calendar every 30 minutes, Airbnb every 3 hours. It is not a full channel manager.

What is iCal?

iCal is the everyday name for iCalendar, an open standard for sharing calendar data between apps. iCal files end in .ics and list events with a start and an end date, so Airbnb, Vrbo, Booking.com, Google Calendar and Bookingmood can all read each other's calendars. (iCal was also the old name of Apple's Calendar app, which is where the nickname comes from.)

Think of it like a language that every booking platform understands, so they can automatically sync booking dates across platforms.

In practice, an iCal calendar is shared through a link. When you export a calendar, the platform gives you a private URL that serves the .ics file. Anyone you give that link to can read your booked dates from it. When you import a link from another platform, your calendar reads theirs the same way. That read-only exchange is the whole trick behind calendar synchronization: no logins, no manual copying, just two calendars pointing at each other.

iCal, .ics, webcal and CalDAV: what's the difference?

You'll run into a few related terms. They're easy to mix up:

Booking platforms use the first two. An iCal link is simply a web address that serves an .ics file, which the other platform reads on a schedule. Platforms don't use CalDAV, which is why an iCal sync can read bookings from another site but never change them.

What's inside an iCal link

An iCal file is plain text. Each booking is an event with a start and an end date:

BEGIN:VEVENT
UID:4f1c2a@bookingmood.com
DTSTART;VALUE=DATE:20260604
DTEND;VALUE=DATE:20260611
SUMMARY:Booked
END:VEVENT

That is a stay from 4 to 11 June 2026. The end date is the check-out day, so the night of the 11th stays free. The UID lets platforms recognize the same booking each time they read the link, so an update or a cancellation replaces the old event instead of adding a new one.

Platforms read only these dates, which is why a sync never carries prices, guest names or messages. Want to see your own? Open your iCal link in a browser, or download it and open it in a text editor.

How iCal sync works, step by step

An iCal sync works through two links, set up once:

• Export: your calendar produces a private iCal link. Anything you allow to read that link sees your booked dates.

• Import: you paste another platform's iCal link into your own calendar, so its bookings show up for you.

After that, the calendars talk on their own. Say you get a direct booking on your Bookingmood site for August 12–15:

1. Bookingmood blocks those dates on its calendar right away.

2. The next time Airbnb and Vrbo read your Bookingmood link, they block the dates too.

3. Your cleaning team sees the booking when you share the vacation home calendar.

Each platform checks for updates on its own schedule. Until the other platforms check again, there is a short window in which the dates still look free there. Keeping that window short, and not opening last-minute dates on several platforms at once, is how you avoid double bookings. It's still far better than updating five calendars by hand every time someone books.

If you want the full walkthrough of connecting platforms, see our guide to vacation rental calendar sync.

How often does iCal sync on each platform?

Platforms don't publish exact intervals, so we measured them. We looked at how often each platform read the iCal links of Bookingmood rentals between 4 and 11 November 2026, across more than 2,000 calendars.

Every platform reads on a fixed schedule. Some also read in between, when someone is active on the platform:

Vrbo, Booking.com and Google Calendar run like clockwork: Vrbo read a typical calendar 47 times a day, Booking.com 11 times and Google Calendar 3 times, day after day. Airbnb's 3-hour schedule comes down to 8 reads a day, but a typical calendar got 9 to 11. The extra reads mostly happened during the day, and often for several listings of the same host within the same minute or two. That points to the host's activity on Airbnb, like clicking Refresh on an imported calendar, which Airbnb lets you do a limited number of times. Guests don't trigger it: when we viewed listings, picked dates and went to the checkout page, Airbnb didn't read the calendar until its next scheduled check. Platforms can change all of this at any time, but it gives you a realistic idea of the window.

What this means for you: a booking on your own website can take up to 3 hours to reach Airbnb, and up to 2 hours to reach Booking.com. If you get many last-minute bookings, that's the window to watch. Bookingmood itself works the other way around: its iCal links are refreshed at least every 5 minutes, and it reads the calendars you import whenever your availability is shown, at most every 5 minutes.

Where to find your iCal link

Every platform puts its iCal links in the calendar or availability settings of a listing. You'll usually find both an export link and a place to import one there:

• Airbnb: open the listing's calendar, go to the availability settings and look for Connect calendars. See Airbnb's help article.

• Vrbo: open the property's calendar and choose import or export. See Vrbo's guides to exporting and importing.

• Booking.com: in the extranet, go to rates and availability and open the calendar sync settings. See Booking.com's partner help.

• Bookingmood: open a unit and click Synchronization. Our iCal synchronization guide covers importing, exporting and custom options.

Copy the export link, not the address of the calendar page: an iCal link usually ends in .ics or contains "ical" or "calendar". One tip for Booking.com: once a sync is set up, don't change availability directly in the Booking.com calendar, as that overrides the imported dates and can lead to double bookings.

What iCal can't do

iCal is old and simple, and that comes with tradeoffs worth knowing:

• Sync is not instant: each platform checks for updates on its own schedule, from 30 minutes to a few hours, so a booking can take a while to block off everywhere.

• Availability only: an iCal calendar shares dates, not prices, minimum stays, guest messages, or review data.

• One way per link: each link carries bookings in one direction. For a two-way sync you connect two links, one in each direction.

• Setup depends on you: if you add a new listing or platform, you have to connect the links yourself.

iCal vs. API sync: which do you need?

Channel managers connect to platforms through an API instead of iCal. Here's how the two compare:

For most hosts, iCal already covers the main risk, which is the double booking. If you run many listings across several channels and adjust prices daily, a deeper two-way integration can save you work.

Keep your policies the same on every channel

Sync keeps your dates aligned, not your rules. If your cancellation policy, minimum stay or check-in time differ between Airbnb and your own website, guests will notice. Set them once, copy them to every platform, and use our house rules checklist to cover the rest.

Is iCal safe?

Mostly, yes. An iCal link is read-only: whoever has it can see which dates are booked but can't change anything. The link itself is the key, though. Share it only with platforms and people you trust, and if it ends up somewhere it shouldn't, create a new link and update it on your other platforms.

Set up iCal sync in Bookingmood

Bookingmood lets you import and export iCal links to and from all major booking platforms, on every plan. That means:

• Bookings made on Airbnb show up on your Bookingmood calendar

• Bookings on your direct website update your Airbnb and Vrbo calendars

• You manage it all from one place

Setup is easy: copy the iCal link from each platform, paste it into Bookingmood, and paste Bookingmood's link into each platform. If you keep your availability in Google Calendar, our Google Calendar synchronization guide walks you through it step by step. The Synchronization page in Bookingmood shows when each platform last read your link.

FAQ

Is iCal the same as Apple Calendar?

No. Apple's calendar app used to be called iCal, but the iCal links booking platforms use are the iCalendar (.ics) format. Apple Calendar, Google Calendar and Outlook can all read them.

Is iCal sync free?

Yes. Airbnb, Vrbo, Booking.com and most other platforms offer iCal import and export at no cost, and Bookingmood includes it on every plan.

How often does iCal sync?

Each platform sets its own schedule. In our measurements, Vrbo reads a calendar every 30 minutes, Booking.com about every 2 hours and Airbnb every 3 hours. On Airbnb, you can click Refresh on an imported calendar to check it sooner. A guest booking doesn't make Airbnb check your calendar first. Bookingmood's own iCal link is refreshed at least every 5 minutes. Calendars you import are read again whenever your calendar is viewed or another platform reads your Bookingmood link, at most once every 5 minutes.

Can iCal sync both ways?

Each link works in one direction. To sync both ways, export your Bookingmood link to the other platform and import that platform's link into Bookingmood.

Does iCal sync prices or guest details?

No. iCal shares booked dates only. Prices, guest names and messages stay on the platform where the booking was made.

Why don't my blocked dates show up on the other platform?

Usually the other platform hasn't read your link yet: wait for its next check, which can take up to a few hours. If the dates still don't appear, check that you pasted the export link and not the address of a calendar page.

What happens if a feed stops working?

Bookingmood retries a failing feed every hour. If it still fails after a day, admins get an email, and after 14 days the feed is turned off. You can turn it back on once the link works again. The iCal synchronization guide lists common errors and how to fix them.

Sync your calendar with Bookingmood

iCal might sound technical, but it's one of the simplest and most effective tools for any vacation rental host. Whether you list on one site or five, an iCal sync keeps your calendars accurate and your double-booking risk low. Start your 14-day free trial and connect your calendars in a few minutes.