Methods and systems are for tripping pipe on a rig floor that is positioned over a well. A measuring device is operated to measure a length characteristic of a first drill pipe in a plurality of separated drill pipes. The length characteristic is inputted into a controller configured to control machinery to hoist the first drill pipe above the drill string, to connect the first drill pipe to the uppermost drill pipe in the drill string, and to operate the drill string to drill into the well. The controller is operated to calculate a first vertical position into which it is necessary to hoist the first drill pipe so that a predetermined clearance distance exists between the lower end of the first drill pipe and the upper end of the uppermost drill pipe in the drill string.