The phases of costing discussed in the paper are those which will be of most interest and use to engineers in shops and offices.An example of the methods of calculating job costs is given, the proportions of the components of the factory costs of various engineering products are illustrated, and the use of mechanical appliances in various calculations is shown to give accuracy and save time in arriving at costs.The functions of a “work-in-progress” account are described in terms, translated from accountancy to their shop equivalents, showing the actual connection between such an account and the production of a department.The effect of inaccuracy, which may so easily occur in shop records, is traced through costs to show the delay and unreliability caused thereby; and the necessity of avoiding this inaccuracy is emphasized.The analysis of the costs of completed jobs gives information which is useful to those engaged in all branches of the industry, and a detailed example of such an analysis is given and described.As an example of the very many practical services given by a cost department, the relation between the rate of production and the proportion of factory overhead expenses in factory cost is cited.