Why iPhone backup always showing failed .even I have space of 4.6gb in 5gb

Hey there ranjit299,

Thanks for reaching out to the Apple Support Communities. If having issues with backing up your iPhone to iCloud, check out the steps below that can help: If you can't back up to iCloud - Apple Support

If an alert says that there's not enough iCloud storage

1. In iOS or iPadOS, go to Settings > [your name].

2. Tap iCloud. At the top, you can check how much iCloud storage you've used.

3. Tap Manage Account Storage or Manage Storage.

4. Tap Backups, then tap the device you're using. Under Last Backup and Backup Size, you can check Next Backup Size. It may take a few minutes for your device to calculate Next Backup Size. 

5. If your backup needs more space than the amount you have available in iCloud, you can: 

- Delete information that you don't need to reduce the size of your backup

- Upgrade your iCloud+ plan to get more space

6. If you still need help, contact Apple Support.

You can find the first section listed above that may help with this issue. If you need further help, click on the link above and check out the steps in the additional sections.

Keep us updated on the results.

Take care!