How much does it cost to replace my iPhone battery?

Cost is approximately $89 (U.S.) at the Apple Store.....make an appointment.....or take the phone to an authorized Apple Service shop.

You can find a list of authorized shops in your area using this link.......Find Locations

The cost of iPhone battery replacement can vary depending on the country or region you reside in. A few factors contribute to this price for replacing your iPhone's battery.

Apple Inc can replace your iPhone battery for a service fee. Their warranty doesn't cover batteries that wear down from normal use. 

iPhone Battery Repair & Replacement