Throw-weight is a measure of the effective weight of ballistic missile payloads. It is measured in kilograms or metric tons. Throw-weight equals the total weight of a missile's warheads, reentry vehicles, self-contained dispensing mechanisms, penetration aids, and guidance systems — generally all components except for the launch rocket booster and launch fuel. While throw-weight may refer to any type of conventional or WMD warhead, in normal usage it almost exclusively refers to nuclear or thermonuclear payloads.