Step length is your height times a factor, 0.415 by default. That figure is a common rule of thumb, not a measured law, so you can change it. Distance is steps times step length. Energy is MET × weight × hours, with the MET for level walking from the Compendium of Physical Activities (2024).
Example. 10,000 steps at 175 cm is about 7.26 km; at 5 km/h that takes about 87 minutes and, at 75 kg, uses about 414 kcal.