Is back glass damage covered by iPhone insurance?

When you say insurance, did you purchase AppleCare+ when you bought your phone? If you did, see this to see what the cost will be to you --> iPhone Repair and Service - Apple Support

As you can see, the back glass with AppleCare+ will cost $29. If you don't have a valid AppleCare+ Plan, the cost will be $199. If you purchased insurance through someone else, like your carrier, you'd have to check with them for what is covered and at how much.

If you're referring to the limited warranty, no, unless it was due to a manufacturing defect.

If you're referring to AppleCare+, yes.

If you're referring to non-Apple insurance, check the policy.

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