iPhone 8 Plus Battery Health

This is normal. The battery starts aging the day it leave the factory. Maybe the other apps are rounding up and the Apple app is rounding down (99.5%). Anyway, you won't even notice a difference of 1% and have nothing to worry about.

The wear gauge is not 100% accurate; nothing is. If you see it continue to drop then I would be concerned. A 1% or even 2% or 3%) is within standard error. Also, check it right after you have charged the phone. That will be the most accurate reading.

TKORob97 wrote:

Same here. My iPhone 8 Plus is only about 1 1/2 months old and its at 99% capacity. Where as my old iPhone 7 plus is about 1-2 years old and is still showing 100% capacity.

There's nothing particular right nor wrong about either reading. There are way too many variables that affect battery health, which is also only an estimate. However, more than likely what you're seeing is perfectly normal.

Another important thing to understand is that most capacity loss is from charge-discharge cycles that inherently reduce capacity. Apple says there's an expectation that an iPhone battery should maintain 80% battery health at 500 charge-discharge cycles.

As was said, possibly a rounding error or even different tools accessing different information. It's really not a big deal. There could be manufacturing variations where one has slightly lower capacity new than the nominal rating and then you're dealing with rounding errors. You're losing capacity every single time you charge it so after a month losing 1% isn't unusual.

But I have seen in few on the reviews that their phone is still at 100%.

My iPhone 8 Plus is showing 99% just after 2 months

Here is the proof https://youtu.be/RRPemQnNVzI

I know 1% may not look like a big deal but it dropped down by 1% in just 1 month and that’s a big deal ...

Same here. My iPhone 8 Plus is only about 1 1/2 months old and its at 99% capacity. Where as my old iPhone 7 plus is about 1-2 years old and is still showing 100% capacity.