How much venom does a black mamba have?

The maximum amount of venom a black mamba has been known to release at a time is 400 mg. The dose that is lethal to 50% of humans is 0.28 mg/kg of body weight. A 150 lb or 72 kg human would have a 50% chance of dying if injected with 20 mg of venom. Black mambas on average inject 100 to 120 mg of venom in a single bite, which, without venom, kills nearly 100% of people.