The interpretation of coincident-loop transient electromagnetic (TEM) surveys is often aided by the transformation of TEM data to apparent conductivity values. Present methods of calculating apparent conductivity have a limited usefulness or require access to a computer. This paper presents an algorithm for calculating apparent conductivity to an accuracy of better than 1 percent for values of the parameter x = σμA/4πt up to 10, where σ = conductivity, μ = magnetic permeability, A = loop area, and t = sample time. This range of x is sufficient for most situations encountered in field work. The algorithm has been programmed for an HP-67 pocket calculator, and the program steps and user instructions are given in standard format. Execution time ranges from 6 to 15 sec. The program should assist the interpretation of TEM surveys in the field.