Are your calendars synchronised right now? The 2-minute test

What is happening to you

You connected your calendars months ago. Since then, you have trusted them. But a doubt sets in: did the booking that arrived last night really travel everywhere? Are the dates you held last week showing on Booking.com?

The trouble is that no platform answers that question. There is no green "synchronisation healthy" light on Airbnb or on Booking.com. When a calendar link breaks, the platform keeps the last data it received and displays it without the slightest warning. A calendar that has been broken for three weeks looks exactly like a calendar that is working.

The only way to know for certain is to test it yourself. Here is the full test. It takes two minutes of handling, it is free, and it calls for no technical skill.

The 2-minute test, step by step

1. Choose a test date

Take a distant date with nothing at stake: a Tuesday in low season four or five months away, outside the school holidays. The point is to be able to hold it and release it without disturbing any real sale. Avoid dates too close to an existing hold: your test date must stay recognisable at first glance.

2. Hold it on the first platform and note the time

On Airbnb (or the platform of your choice), hold that test date by hand, directly in the listing's calendar. Note the exact time you did so, to the minute: that is the starting point for your stopwatch. If you manage several properties, test them one at a time, as each has its own connections.

3. Watch for it arriving on the second platform

Open the second platform's calendar and watch for the held date appearing. There is no point refreshing every five minutes: platforms read the links in cycles. Reference points recorded in August 2026: every 3 hours for Airbnb (a figure published by the platform), of the order of 2 to 3 hours as observed for Booking.com, every 30 minutes for Abritel and Vrbo (a published figure), often 8 to 24 hours for Google Calendar. The detailed figures are in our guide to iCal synchronisation times, platform by platform.

The verdict is simple: if the test date appears in less than one full cycle, that direction of synchronisation is working. If it is still not there after 24 hours, that direction has failed.

4. Check from a guest's point of view, in a private browsing window

Open a private browsing window and look for your listing on the second platform the way a guest would. Try to select the test date: it should be unavailable. This public-side check matters, because it is what the person booking sees, and the guest view sometimes differs from your host calendar. Think of the telephone as well: the app and the website sometimes show different states, and a large share of guests book on a mobile.

5. Test the journey the other way

Release the test date, then run steps 2 to 4 again in the other direction: hold a date on the second platform and watch for it arriving on the first. Synchronisation is two independent journeys: an import and an export on each side. One can work perfectly while the other is dead. Testing one direction only proves half the system.

When everything is finished, release the test date everywhere. That is the classic thing to forget in this test.

Write down what the test taught you

Take thirty seconds to record the result in a note or a spreadsheet: date of the test, direction tested, time held, time it appeared opposite. There are two benefits. First, you will learn the real rhythm of your platforms, often different from the general figures, and you will be able to tell a normal delay from a genuine outage. Second, if you ever face a double booking, that history becomes part of your case: it shows that your set-up worked and that you were checking it seriously.

Read what your calendar link really contains

The stopwatch tests the whole chain. To move faster on one particular doubt, you can read directly what a calendar link carries.

Copy the calendar link (the one you pasted into the platform that imports it) and open it in a browser. Three outcomes are possible:

• Text appears or downloads, beginning with BEGIN:VCALENDAR. The link is alive. Each BEGIN:VEVENT block is a booking or a held period, with its dates on the DTSTART and DTEND lines. They read without a translator: DTSTART;VALUE=DATE:20261224 means a start on 24 December 2026. Check that your recent bookings are there. If you find unexpected held dates, of the "Not available" kind, you may have found the source of dates wrongly held, as in the calendar conflicts between Airbnb and Vrbo.
• An error or a blank page. The link is dead or momentarily unreadable. If it is the platform refusing the link at the moment you paste it, our guide on the invalid .ICS link error gives the repair step by step.
• An ordinary web page, with photographs and buttons. This is not a calendar link: it is most likely the address of your listing, pasted by mistake when you made the connection.

One small detail that matters: if the link begins with webcal://, replace that beginning with https:// before opening or pasting it.

The honest admission: this test covers now, not tomorrow

This test is reliable, and it has just given you a real answer: at this moment, your calendars are talking to each other, or they are not. But let us be frank about its limits. It photographs one moment. It says nothing about six o'clock tomorrow morning, when a platform replaces a link without warning, or switches off an import after a setting is changed.

And synchronisation outages are born in exactly that way: without warning, between two checks. You are not going to hold a test date every morning, nor read your calendar links every evening. Nobody does, and that is quite normal.

Do the rough sum: checking by hand once a week leaves on average 3 to 4 days of blind spot between an outage and its discovery. Checking every 30 minutes brings that blind spot down to less than an hour. The test is the same in both cases. All that changes is the repetition, and repetition is what protects you.

That is exactly what continuous watching is: this test, run over and over on your behalf. A service that reads each of your calendar links every 30 minutes (every 15 minutes on the Pro plan), compares what they contain, and alerts you by email as soon as a link stops answering or two bookings overlap. A health screen shows the last successful reading for each calendar. And if a link fails, the last known good version of your calendar is still served to the platforms: a passing outage does not turn into an empty calendar in which all your dates become bookable again. The question "is it working, right now?" has an answer at all times, not only on the day you think to ask it.

If your test has just failed, do not leave it there: the seven causes of outage, ranked by likelihood and each checkable in a minute, are in our guide on why your Airbnb calendar has stopped synchronising. And if you discover two bookings on the same dates, follow without delay what to do about a double booking.