Legacy generally uses real-world metric measurements for in-game distances and times. Distances are measured in meters; mass is measured in kilograms; time is measured in seconds. Typical SI scaling is allowed; large distances can be measured in kilometres; large masses might be measured in tonnes; time can be measured in minutes, hours, or days.

However, during combat, time is measured in ten-second rounds. This is done only during combat, and is used to make each round in combat a fairly self-contained unit. Further, masses are not generally tracked, and a character instead has the amount that they can carry limited according to their inventory slots.