If you wish to migrate Google Contacts to iCloud, be aware that moving contacts from one service to another is not as simple as it seems. Many users assume that with both iCloud and Gmail accounts, and contact sync enabled on the iPhone, the services will continuously sync data. However, the reality is different.
In fact, I once believed my Gmail contacts were syncing to iCloud until I checked the iCloud contacts. The answer turned out to be: no.
To transfer contacts from Gmail to iCloud, you must follow specific steps on your computer. Here's the simplest way to do it.
Transferring Contacts from Gmail to iCloud
Firstly, log in to your Gmail contact management account on the web. If using the new Contacts Preview version, switch to the old version before proceeding with the next steps.
Here, click on the More button on the screen, select Export.
On the Export screen, choose vCard, and click on the Export button. Save the file.
Now, log in to your iCloud account and select Contacts. (If you don't have an iCloud account, proceed with iCloud Sign Up)
Click on the small settings icon at the bottom left of the screen, choose the Import vCard option. Select the vCard you downloaded from Google.
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Wait a few minutes for the device to import all the data; now, all your Gmail contacts are in iCloud. Afterward, simply transfer contacts from iCloud to Gmail for use across various devices, learn how to transfer contacts from iCloud to Gmail here.