Atomic partitions of ∆ρ(r) also lend themselves to construction of various metrics intended to quantify the CT character in a given excitation. This is an important descriptor in view of TD-DFT's well known tendency to underestimate long-range CT excitation energies, sometimes to the point of predicting spurious low-lying states in large systems. Some of these CT metrics have more desirable properties than others, such as correct normalization and invariance to unitary transformations of the MOs. The present work advocates for the use of direct measures of exciton size that correspond to well-defined statistical quantities, rather than ad hoc constructions. The former include the RMS electron-hole separation (d exc ), which is expressed in terms of the particle and hole densities ∆ρ elec (r) and ∆ρ hole (r). The mean separation between the centroids of these quantities (d - e-h ) can also be used, although it vanishes in centrosymmetric systems, but in such cases a charge-displacement metric (d CD ) can be used instead. These quantities are directly interpretable and readily computable using third-party software, based on formatted output from various electronic structure programs. The TheoDORE program is especially recommended, as it implements various measures of exciton size that are grounded in proper expectation values, as well as CT numbers Ω A→B that properly account for non-orthogonality of the AO basis functions. Much of this functionality exists in the Q-Chem program also, without the need for third-party software. The author hopes that this Perspective will lead to better understanding and more erudite discussion of precisely what is being visualized or quantified when discussing the output of TD-DFT calculations.