How much does a battery replacement for iPhone 11 Pro Max will cost?

Same price as mentioned above. $89 (US) at your Apple Store Genius Bar.

You can use this to make an appointment --> iPhone Battery Service - Apple Support

Hello Izngwenalthea!

Yes, that battery definitely needs to be replaced!

According to the “Get an Estimate” tool in here, the battery replacement will cost $90 United States Dollars (USD).

Have a nice day, and good luck!

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