How much THC is in Hemp? THC Levels in Hemp Explained – Why 1% is better than 0.3% THC Hemp. What is hemp? Hemp is just cannabis that has very low levels of THC. People often ask how much THC is in hemp? We discuss what the law says, why the law is silly, and why 1% total THC hemp could save the CBD industry. hemp vs weed difference. What is hemp?