1 ) A network bandwidth sizing system comprising at least one branch having two or more client computers connected to a datacenter to send the input to the datacenter (uplink) and to receive the output from the datacenter (downlink); the said datacenter having one central server comprising database server, web server and application server for receiving, storing, processing the input from the user and sending the output to the user through a communication network, wherein the said system characterize in allocating the bandwidth per branch of networks of an enterprise taking in to account both throughput and response time requirements, the said system having processor configured to execute programmed instructions to: a) Compute a throughput and a think time per class of branch of network of the enterprise based on the user defined input; b) Compute an initial value for bandwidth per branch of network of the enterprise, which satisfies the throughput requirement, from known throughput of step (a); c) Compute a feasible value for bandwidth per branch of network of the enterprise, which satisfies the response time requirement, using the Approximate Mean Value Analysis (AMVA); and d) Compute a final value for sizing bandwidth per branch of network of the enterprise, which satisfies both throughput and response time requirements, using the AMVA.