In single-phase shell-and-tube heat exchangers, thermal performance prediction is customarily accomplished with an idealization that the number of baffles used is very large and can be assumed to approach infinity. Under this idealization, the temperature change within each baffle compartment is very small in comparison with the total temperature change of the shell fluid through the heat exchanger. Thus the shell fluid can be considered as uniform (perfectly mixed) at every cross section (in a direction normal to the shell axis). It is with this model that the mean temperature difference correction factor is normally derived for single-phase exchangers. In reality, a finite number of baffles are used, and the condition stated above can be achieved only partially. In this article, a comprehensive review is made and new results are derived where needed to assess the influence of a finite number of baffles on heat transfer performance for 1-1, 1-2, and 1-N TEMA E, 1-2 TEMA J, and 1-2 TEMA G and H single-phase shell-and-tube exchangers. It is shown that the number of baffles required to achieve the performance within about 2% of an exchanger with an infinite number of baffles varies with the type of exchanger and the performance parameters. The new results are presented in tabular form.