How long does methadone stay in your system?

Methadone half-life: The half-life of Methadone is 15 to 60 hours. It takes five times the half-life to leave your system. Therefore it could take anywhere between 75 hours to 300 hours to clear your system. This is with chronic use. The half-life for most people is approximately 25 hours meaning that would take approximately five days and five hours to leave your system completely.