Swimming across a rushing river, sneaking down a dungeon corridor, scaling a treacherous mountain slope—all sorts of movement play a key role in fantasy gaming adventures.

The GM can summarize the adventurers’ movement without calculating exact distances or travel times: “You travel through the forest and find the dungeon entrance late in the evening of the third day.” Even in a dungeon, particularly a large dungeon or a cave network, the GM can summarize movement between encounters: “After killing the guardian at the entrance to the ancient dwarven stronghold, you consult your map, which leads you through miles of echoing corridors to a chasm bridged by a narrow stone arch.”

Sometimes it’s important, though, to know how long it takes to get from one spot to another, whether the answer is in days, hours, or minutes. The rules for determining travel time depend on two factors: the speed and travel pace of the creatures moving and the terrain they’re moving over.