What is Per Diem in drayage?

In drayage, per diem is the daily charge an ocean carrier or equipment provider bills for keeping a container or chassis in use beyond the free time allowed. The Latin phrase means "per day," and that is exactly how it works: once the free-time clock runs out, each additional day the equipment is out costs a fixed daily rate until it is returned.

Per diem is closely related to detention but is specifically the equipment-use component — it is the rent on the container and chassis, distinct from demurrage (rent on the box sitting inside the terminal). Chassis per diem in particular is a frequent line item because a trucker may hold a chassis for several days across a multi-stop move.

Because per diem accrues automatically and daily, carriers minimize it with tactics like street turns (reusing an empty for the next export rather than returning it) and disciplined equipment return before the last free day.