Generally, four hours.
A “window of impairment” that lasts anywhere from three to ten hours, depending on the THC dose, the mode of ingestion, and the consumer’s previous cannabis experience.
Researchers found that cannabis consumers recovered most of their driving-related skills within five hours of inhaling 20mg of THC. Consumers who consumed the same amount of THC via an edible took longer to recover their driving skills. Most cannabis edibles in legal markets are dosed at 10mg per serving, and 100mg total THC per package.