Surge protection is offered in amounts relating to a joule rating. Joules are the standard unit for measurement of energy released over a period of time. As a general rule, the more joules the better. This means that a surge protection device can handle either a single large surge or multiple smaller surges.
With that in mind, deciding how much surge protection you need will depend on various influencing factors. For instance, how much surge is required will depend on the value of the equipment being protected, as well as how many devices require protection. Typically, 1,000 Joules will be adequate for smaller electronics, whereas 2,000-3,000 Joules should provide sufficient protection for everyday electronic devices such as computers, printers, and copiers.