Abstract The measurement of the volume of blood cells is important for clinical diagnosis and patient management. While digital holography microscopy has been used to obtain such information, previous off-axis setups usually involve a separated reference beam and are thus not very easy to implement. Here, we use the simple in-line Gabor setup without separation of a reference beam to measure the shape and volume of cells mounted on glass slides. Inherent to the in-line holograms, the reconstructed phase of the object is affected by the virtual image noise, producing errors in the cell volume measurement. We optimized our approach to use a single hologram without phase retrieval, increasing distance between cell and hologram plane to reduce the measurement error of cell volume to less than 6% in some instances. Therefore, the in-line Gabor setup can be a useful and simple tool to obtain volumetric and morphologic cellular information.