The AirPods 4 service will last at least six hours of playback time, this is greatly reduced when using noise cancelling. This estimate is under the best case scenario; assuming the user isn't switching on and off noise cancelling every moment, in which case the battery would be depleted unless infrequently used. So one can presume that AirPods 4 with features switched on will last around four to five hours at best and for an average user, this translates into a good amount of usage.