30 kilograms. According to the information of official website, the State General Administration of Sport, adults can hold 40kg for barbell bench press, indicating that their physical strength and muscle endurance can bear dumbbells weighing 15kg with one hand, that is, 30kg with both hands. Barbell bench press belongs to free weight training, and the training effect is better than fixed equipment. It can be divided into three forms: lying flat, upward oblique and downward oblique, focusing on different parts of pectoralis major and mainly exercising the whole pectoralis major.