In older adults’ everyday life, time-based prospective memory (TBPM) is relevant as health-related intentions are often part of daily activities. Nonetheless, it is still unclear which task-related factors can potentially moderate the magnitude of age-related differences, such as duration of the PM target time (the time-window within which an individual must complete a given TBPM task), the frequency of the TBPM tasks, and the criterion chosen to compute PM accuracy. The present meta-analysis aimed to quantify age-related differences in laboratory TBPM tasks, and to investigate how specific task-related factors potentially moderate the magnitude of age effects. The results showed that age effects consistently emerged among the studies, with older adults showing lower TBPM performance and checking the clock less often than younger adults, especially for shorter intervals (e.g., ≤ 4 min). Furthermore, the results indicated that the duration of the PM target time interacted with the frequency of the PM task, suggesting that learning effects may attenuate the magnitude of age differences in TBPM performance. The results are discussed in terms of potential implications about the possible cognitive processes involved in TBPM and aging, as well as in terms of robustness of the TBPM laboratory paradigm in aging research.