Electronic editor for formulae for calculating the price of a service designed to define the formula in a format directly readable by an electronic costing system designed to establish the price of a service using information on the service consumed contained in consumption variables. The editor includes an electronic calculator capable of defining the calculation formula and storing it in the first storage unit for storing information. The calculator includes an acquisition module having a tree structure formed from nodes, each node being associated with a calculating operation designed to be executed by the costing system to establish the price of the service and defining the order for carrying out the operations by the electronic costing system, and a module for automatically converting the acquired tree structure into a directly readable format by the electronic costing system and storing the converted tree structure in the first storage unit.