Barchans are a common sand dune type found on both terrestrial and Martian surfaces. The morphometry of individual barchans and barchan groups has been measured extensively in past studies. Within each dune field, similar sized barchans are observed to be abundant, but previous morphometric studies typically do not compare their results with those from many other dune fields. This study includes diverse dune fields on both Earth and Mars concentrating mostly on the dimensionless geometric variabilities of their barchan populations. The geometries show a degree of similarity between barchan populations despite the different environmental characteristics from one dune field to another. This project made use of NASA’s public photos, Mars Reconnaissance Orbiter CTX Imagery, Google Earth, and Digital Globe’s free, high-resolution imagery. The key dimensions of more than 1500 barchans, representing dunes from 14 terrestrial and 5 Martian dune fields, were measured using the Google Earth ruler tool and Photoshop CC software. Determining the variation of barchan geometry provides evidence of similar barchan characteristics on a large scale and creates a foundation for future research. Documenting these barchan geometries provides a better understanding of the geomorphic time-space sequences, evolutions, geospatial distributions of barchan populations, and may provide a robust basis for the classification of barchan morphologies according to dimensionless geometry.