iPhone 17 battery maximum capacity at 91% after one year

Ideally, the battery will decline about 1% for every 50 Charge Cycles.

306 divided by 50 equals = 6%.

So, if the battery was declining ideally, it would be at 100% minus 6% equals 94% Battery Health / Maximum Capacity.

The current reading of 91% is pretty good though, since the battery does not decline at exactly the same rate. Some months, it might not decline at all, then drop 2% the next month. This is normal. Batteries are chemical devices.

For best battery performance, set the battery up for Optimized Battery Charging . Ignore Charge Limits so the iPhone will charge to 100%. Connect the phone to the charger at night and leave it connected all night.....every night.

It won't help to be checking the battery settings all the time. The battery is going to do what it is going to do.

All that you really need to remember is to replace the battery when it dips under 80% Maximum Capacity. That will likely be a little over a year from now.

Months don't matter. Charge Cycles do.

Someone could own a phone for 10 months and not use the phone that much. Another user could own a phone for 10 months and use it heavily. The Maximum Capacity would be completely different for these two users.

We need to know how many Charge Cycles the phone has completed to be able to answer your question.

sharvari227 wrote:

I bought my iPhone 17 in September 2025 and now as of September 1st 2026, my battery maximum capacity is at 91%

Is this considered to be good or bad? How should I maintain my battery’s maximum capacity?

Without knowing the number of Cycle Charges, it's hard to know how your battery is doing. Read this and it may help you --> Battery Health Decline - Should You Worry… - Apple Community

The following was included in the original response, but somehow did not appear:

Ideally, you would see that your battery has completed about 450 Charging Cycles at this time.