My iPhone 13 battery dropped 4% in two months

Batteries degrade over time with usage due to chemical aging, that's just how they work.

You can expect about a 1% drop per month with average use on an iPhone. This is an approximation, that is why it may be plus or minus a few percent on a month to month basis.

Apple recommends replacing it when it reaches 80%. To check your battery health, go to Settings > Battery > Battery Health.

iPhone Battery Replacement.

iPhone Battery Repair & Replacement - Apple Support

About Lithium Ion Batteries

iPhone battery and performance - Apple Support (IN)

Here are some tips on maximizing battery life.

Batteries - Maximizing Performance - Apple

daniyal263 Said:

"Battery health: My iphone 13 battery drop 4% in two months. Is it normal?? and how i can maintain the battery health"

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Battery Health Degrade:

Unfortunately, there is no way to determine why, nor when, the Battery heath degraded. They do so as they are used.