A mechanism for guaranteeing deterministic bounded tunable downtime for live migration of virtual machines (VMs) over reliable channels is disclosed. A method of the invention includes receiving a maximum downtime of a VM during a live migration of the VM from a source host machine to a destination host machine, determining a capacity of a network channel on which the VM is live migrated to the destination host machine, calculating a number of memory pages of the VM left to be transferred as part of the live migration before the VM is stopped, wherein the calculating of the number of memory pages is based on the received maximum downtime and the determined capacity of the network channel, and stopping the VM when the calculated number of memory pages remain to be transferred in order to transfer those memory pages to the destination host machine.