There is no definitive answer to this question as it depends on a number of factors, including the breed of bantam, the quality of care they receive, and luck. However, on average, bantams do tend to have a longer lifespan than full-sized chickens. This is likely due to their smaller size, which means they experience less wear and tear on their bodies and are less likely to succumb to injuries. Additionally, their smaller organs are less likely to fail and they are less likely to develop obesity-related health problems.