An age band is a range of ages used by insurers to determine premium rates. Rather than setting a unique premium for every single age, insurers group ages into bands — for example, 18-24, 25-29, 30-34, and so on in five-year increments. While you stay in one band, your age does not change your price; when you move into the next band at renewal, your premium usually rises. Age bands reflect the fact that health care costs generally increase with age. Understanding age bands helps you compare plans accurately. Some insurers use narrower bands or single-age pricing.