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The battery life is calculated based on the following format listed as follows.
1)Battery Life Stats give you better understanding of the screen on time [SOT] and battery life which you can expect in real world.
2)Battery life depends on one's usage [light / medium / heavy], task [video watching / gaming / camera] & network [WiFi / 5G / 4G / 3G].
3)Based on one's usage, task & network above SOT & Battery Life will increase / decrease respectively.