The purpose of the Rate of Perceived Exertion (RPE) scale in exercise is to provide a subjective measure of exercise intensity based on how hard an individual feels they are working. It allows individuals to gauge their effort levels during workouts, facilitating adjustments to their training intensity to meet fitness goals. The RPE scale typically ranges from 0 to 10, where 0 represents no effort and 10 represents maximum exertion. Using the RPE scale helps maintain safe exercise levels, encourages self-awareness in physical activity, and can be particularly useful in customizing training programs for various fitness levels.