The computer-implemented method for apportioning bandwidth in storage systems may include (i) identifying a plurality of storage media and at least one workload that is assigned a quantity of credits at the beginning of a predetermined time period that regulate a volume of bandwidth for input/output requests from the workload, (ii) detecting an input/output request from the workload, (iii) deducting, before fulfilling the input/output request, a number of credits from a current number of credits available to the workload based on an estimated quantity of bandwidth consumed by the input/output request, (iv) measuring an actual quantity of bandwidth consumed by the input/output request, and (v) adjusting the current number of credits available to the workload for the predetermined time period based on a difference between the estimated quantity of bandwidth and the actual quantity of bandwidth.