Background and purpose: Most of the previous studies evaluating lung volume of pectus excavatum (PE) patients were based on spirometric measurements. We aimed to calculate lung volume of patients with PE and compare them with lung volume of patients without chest wall deformity using CT volumetry. Methods: After institutional review board approval, preoperative chest CT of PE patients who underwent minimal invasive procedure between January 2012 and February 2018, were evaluated retrospectively. As a control group, age and sex matched patients who underwent chest CT scan in the same period were enrolled. Total, right and left lung volumes were calculated using an automated software. Haller indexes were measured for both groups. Lung volumes and Haller indexes compared between the two groups. We also compared left and right lung volumes in both groups. We evaluated whether there is a correlation across the Haller index and total lung volume. Results: Total, right and left lung volumes were not statistically different between the two groups. While left lung volumes were significantly smaller in PE group (p = 0.041), there was no significant difference between the left and right lung volume in the control group (p = 0.12). Haller index and total lung volume showed no significant correlation between patients with the same age and gender (p = 0.14, R = −0.3). Conclusions: PE deformity does not reduce lung volume when compared to age and sex matched control group. Quantitative CT volumetric evaluation of lung gives valuable data about lung volume.