My new iPhone 17 Pro's battery health dropping to 99% with only 58 charge cycles

You are exactly where you should be. The phone is expected to last 1000 charge cycles before the battery needs replacing when it falls below 80%. That equates to 1% for every 50 Charge Cycles, but the Battery Health drop is not linear, meaning some months may not drop at all and other months may drop more. There is not a hard link that drops the Battery Health by 1 when you reach each 50 Charge Cycle interval, it is just the average you should expect for the life of the battery.

Himanshuyadav22 wrote:

I bought a new I phone 17 pro on July 22 and my cycle count is currently 58 but my battery health has dropped to 99%. Why is this happening. Can you please help me? I have previously owned the I phone 16, I phone 15, I phone

13 as well. Their battery health would drop by just 1% after around six month usually when the cycle count exceeded 150. But this time my I phone 17 pro battery health has dropped to 99% with only 58 charge cycle. Why is this happening

Your battery health is 100% normal and a drop of 1% per 50 cycle charges is what is expected "on average." Read this to better understand --> Battery Health Decline - Should You Worry… - Apple Community

iPhone 13 did not show cycle count, so I'm not sure why you think it did? Cycle Count didn't appear until iPhone 15 and newer.