Embodiments of an arm-worn rangefinder device includes a rangefinder body and a switch. The rangefinder body is shaped for coupling to a user's arm and has an electronic rangefinder circuit operable to emit an energy beam directed at a selected target, to receive a reflected beam from the target, and to calculate the target's approximate range based on properties of the reflected beam and indicate the calculated approximate range to the user. The switch is coupled to the rangefinder body, and the user can use the switch to selectively actuate the rangefinder circuit.