Hollow carbon nanofibers (CNFs) are being explored as catalyst supports because of their unique properties. Internal versus external loading of metal nanoparticles impacts catalytic performance; we developed a fast and accurate geometric analysis method based on two-dimensional transmission electron microscopy (2D TEM) images to estimate Pd internal versus external loading percentages. Three different Pd-loaded CNF catalysts were prepared using methods reported in the literature to yield different amounts of Pd inside loading. Results indicate the percentage of inside-loaded Pd increases as expected in the three samples (from 22.7 ± 17.8%, to 47.2 ± 22.8%, to 71.4 ± 19.7%, based on Pd nanoparticle number). We compared percent inside loading values for one segment of a Pd-loaded CNF using our method and three-dimensional scanning transmission electron microscopy (3D STEM), and observed adequate agreement (27.8% vs 32.7%). Our geometric analysis method is proposed as a more straightforward and fast way to evaluate metal nanoparticles on tubular supports.