A method in a base station for calculating a power relating to a first radio access is provided. The power is to be shared with a second radio access within the base station. The base station communicates with a number of user equipments using the first radio access. When the base station has estimated a statistic power distribution of transmit power to said user equipments during a time interval, it calculates a margin of power not to be shared with the second radio access, based on the estimated statistic power distribution. The base station further calculates a power to be shared with the second radio access, based on said margin of power.