The best size trampoline for exercise ultimately depends on individual preferences and needs. However, many people find that mini trampolines ranging from 38 to 48 inches in diameter are ideal for home use due to their compact size and versatility. Larger trampolines, such as those with diameters of 50 inches or more, may be better suited for outdoor use or advanced exercises that require more space. Ultimately, the best size trampoline for exercise is one that fits your available space and fitness goals while providing a safe and enjoyable workout experience.