The burn time is the total operating time of a rocket engine. For solid-propellant rocket motors, this is the more-or-less unstoppable period of thrust until all of the propellant is consumed. For liquid-propellant rocket engines, it is the rated thrust duration of the motor for a single operation – a quantity greater than the thrust time of the motor in actually use on a particular stage. The total tested or rated operating time of a liquid motor between overhauls (if it is reusable) is typically many times the total rated operating time per use.