Purpose <p>The peritoneal cavity is a complex area of human anatomy. Although the general anatomy and subdivisions of the cavity have long been understood, no studies have investigated its overall morphology and individual variability. This study aimed to create a three-dimensional (3D) model of the peritoneal cavity and perform a principal component analysis (PCA) to determine its average shape and individual variability. Methods: Thirty archival abdominopelvic computed tomography (CT) scans were used to create 3D models of the peritoneal cavity. A PCA was performed to determine areas of variation. Results: An average 3D model of the peritoneal cavity was created. There was a high degree of both intra- and inter-observer reliability. The main area of variation between individuals was a change in width in the coronal plane and thickness in the sagittal plane. Differences between males and females were also investigated, as well as in high vs low BMI individuals. Conclusion: The peritoneal cavity exhibits consistent patterns of shape variation that are quantifiable in three dimensions. Our findings lay the groundwork for future anatomically informed tools in surgical planning, education, and device design.</p>