How many charge cycles does a smartphone battery last?

How to get close to this number

Work backwards from the phone in your pocket. Most people notice a meaningful drop in battery life somewhere in the second year of ownership, and most people charge roughly once a day. Multiply those two everyday observations together and you land on the answer without knowing anything about lithium chemistry. This is estimation from lived experience, which is often the strongest evidence available.

The concept that trips people up is the cycle itself. A cycle is a full charge worth of energy, not a plug-in event, so topping up from eighty to a hundred percent four times counts as one cycle rather than four. Anyone counting plug-ins will badly overestimate how fast their battery is ageing, and anyone assuming a cycle is a calendar day will get the timeline wrong too.

It is also worth saying plainly, as the explanation does, that this is chemistry rather than planned obsolescence. Lithium-ion cells degrade through unavoidable physical processes, accelerated by heat and by sitting at very high or very low charge. The rated figure describes retention of a stated fraction of capacity under manufacturer test conditions, and real-world results vary widely with how the phone is used and how warm it gets.