A route calculation system includes a collection unit that collects a current link traffic volume and a link power consumption for each link included in a network; a link cost calculation unit that estimates, for each link, an increase in the link power consumption due to the request flow based on the current link traffic volume, the link power consumption, the request flow, and the characteristic, and calculates a link cost value based on the increase in the link power consumption; and a route determination unit that determines, as a route for the request flow, a route that has the smallest sum of the link cost values of each route connecting between any nodes, thereby reducing the power consumption in the entire network for a request flow.