Methods and apparatus for dynamic bandwidth allocation are disclosed. An example method includes determining, by a network device, at least one of a congestion state of a packet memory buffer of the network device and a congestion state of an external packet memory that is operationally coupled with the network device. The example method further includes dynamically adjusting, by the network device, respective bandwidth allocations for read and write operations between the network device and the external packet memory, the dynamic adjusting being based on the determined congestion state of the packet memory buffer and/or the determined congestion state of the external packet memory.