Battery calibration refers to the process of calibrating or resetting the battery measurement system in electronic devices. It helps the device accurately determine and display the battery's remaining charge levels. Full definition
I faced battery calibration issue and after a full drain / recharge I am getting over a day of backup with moderate usage. (gogi.in)
While it's a good idea to use any included utilities or just follow instructions specific to your laptop, you can also perform battery calibration without any specialized tools. (howtogeek.com)
Some modern devices may not require battery calibration at all. (howtogeek.com)