How long does it take to Replace an iPhone battery at an Apple Store?

If things are not too busy. Even if they are not, it will likely take 45-60 minutes. I assume that you have confirmed that the shop has a replacement battery in stock.

Don't know what time your appointment might be, but I would have a few errands to run or plan to grab some lunch after you drop the phone off.

Need more power? An Apple Store or Authorised Service Provider near you can replace your iPhone battery. See the associated cost by cover type.

iPhone Battery Repair & Replacement