Backing up your contacts is an essential practice for all mobile users both for the purpose of safety and for times when you are moving your stuff from an old device to a new one. Generally, keeping a backup of your files is wise because a lot could happen that will cause you to lose your files (theft, device malfunction, mistakes from the user, etc.)
Fortunately, creating a backup of your contacts on your Android device is easy. However, you need to have your Google account signed in on your device or at least have an existing Google account (same with your Gmail).
Follow the steps below to backup your contacts.
1. Go to Settings > Accounts and sync > Add account > Google > Sign in.
2. Sign into your Google account or create a new one if you do not have one already, by clicking on the Create button and filling in your info into the fields provided.
3. After signing in and or creating a new account, click on your Google account.
4. Check all the boxes or toggle on the data you want synced to your Google account. In this case turn on Contacts or People details, to sync your phone contacts to your Google account.
5. When you’re done, click on the options menu (probably a three-dot menu style) and select the sync now option. This will automatically sync your contacts (and other data you selected) to your Google account.
6. To see your synced contacts, visit https://contacts.google.com and sign in with your Google account.
You can also access your contacts from anywhere, from any PC or mobile device in the world. Just visit https://contacts.google.com and sign in to your Google account and voila, Contacts!