The above image is screen shot of official announcement made by WhatsApp regarding their new deal with Google Drive , in result of which your WhatsApp backups on Google drive space will not be counted, Starting from November 12, 2018.Yes you can save your WhatsApp backups for free on Google Drive without thinking of space limits.

However , Accounts which are not active for about one year, Their backups will be deleted from Google Drive automatically.

How to setup Google Drive backup?

1. Install / update latest WhatsApp on your phone.
2. Go to settings => chats => chat backup and setup Google Drive backup.