The two-dimensional solution for annular fins, given in graphical form with the efficiency plotted versus the design-parameter group, (b − a)[(2h)/(kw)]1/2, supplies needed design information for fins of small height-to-thickness ratio and large height-to-inner radius ratio. The one-dimensional solutions previously given for annular fins are accurate for height-to-width ratios of the order of 10 or more, while the two-dimensional results for rectangular fins are useful as approximations to annular fins when curvature is not large. With height-to-width ratios less than 10 and for annular fins with large curvature, design of fins can be computed with the results presented in this paper.