As far as we know, Kalas led an unspectacular but luxurious life. His father was Harpalus, who was close with Alexander the Great but, when given a post used it to widen his own pocket. He was caught twice of doing this, then eventually fled to Greece, where he had a number of escapades before eventually being executed in Crete.
One of Kalas’ first forays was under Philip II in an ill-fated expedition that was destroyed by Memnon of Rhodes shortly after Philip’s death. Laster on, he joined with Alexander in his expedition and had infinitely more success, and some retribution, leading the famed Thessalian cavalry (named by Diodorus Siculus as the Cavalry of the Year) in the Battle of the Granicus.
Perhaps due to his success, he received the satrapies of Phrygia and Paplagonia. During this time, he attempted to add Bithynia to his and Alexander‘s territories, but was defeated by Bas, grandfather to Nikomedes I. Perhaps Kalas died in this expedition. We don’t really know, but before Alexander died Demarchos succeeded him as satrap.