How much time would a federal inmate serve if he was sentenced to 48 months?

A federal inmate sentenced to 48 months would typically serve about 85% of that time due to good behavior, resulting in roughly 41 months in prison. However, this can vary based on factors such as the nature of the crime and any additional time for disciplinary actions. It's also possible for inmates to earn additional credits that could reduce their time further. Ultimately, the precise release date can depend on various circumstances and the specific federal facility's policies.