Charging an iPhone to 80% instead of 100% can help reduce long-term battery wear, but that does not mean everyone should use the lowest available charge limit.
On iPhone 15 and later, Apple lets users choose a Charge Limit between 80% and 100% in 5% increments. The setting is found under Settings > Battery > Charging. Apple may also recommend a limit based on how you use and charge your iPhone.
The reason to use a lower limit is simple: lithium-ion batteries age partly according to their charging pattern, and spending less time at a very high state of charge can help reduce chemical aging. For someone who finishes most days with plenty of battery remaining, an 80% or 85% limit can therefore make sense.
There is a trade-off. A lower limit deliberately gives you less usable battery each day. If you regularly reach the evening with a nearly empty iPhone, charging to 100% may be more useful than preserving a little extra long-term battery health.
A middle setting such as 90% or 95% can be a useful compromise for people who want more daily capacity without keeping the battery completely full as often. There is no single percentage that is right for every iPhone owner.
When the limit is set below 100%, the iPhone may occasionally charge all the way to 100%. Apple says this is intentional and helps maintain accurate estimates of the battery’s state of charge.
If you leave the limit at 100%, Optimized Battery Charging can instead reduce the amount of time the iPhone spends fully charged by delaying the final part of charging when it predicts the phone will remain plugged in for an extended period.
For most people, the best setting is the lowest charge limit that still comfortably gets the iPhone through a normal day. Heavy users may be better served by 100%, while lighter users have more room to reduce the limit without noticing the lost capacity.