Introduction: Mechanical properties of cells have been identified as label-free biomarkers of cell state and have been associated with their biological functionality [1]. Microfluidics has enabled precise control and manipulation of cells within the constriction-based cytometry device [2]. However, the current approaches for assessing mechanical parameters of suspended cells using constriction-based microfluidic devices have several limitations. We propose a new methodology to analyze the mechanical properties of suspended cells using numerical simulations and an extension of the quasi-linear viscoelasticity theory [3]. Methods: We designed and fabricated a 12-channel cell deformation device based on microfluidics (cDC device). The device comprises four modules: a fluid inlet, a filter to block large cells and particles, a set of 12 channels each with a constriction, and a fluid outlet. Through FSI simulations, we assess the differential pressure within the constrictions and model cell deformation in response to this pressure. We present a practical procedure for evaluating the mechanical parameters of individual cells, validated through experimental analyses with suspended cells. Results: The proposed methodology successfully addresses critical limitations in existing techniques, offering a valuable tool for harnessing the potential of microfluidic devices. Numerical simulations confirm the effectiveness of our approach in evaluating pressure differentials and modeling cell deformation. Application of this methodology to experimental scenarios with suspended cells underscores its appropriateness and potential for yielding meaningful results. Our developed methodology is positioned as a pivotal tool overcoming current limitations and maximizing the potential of microfluidic devices. Critical examination of current techniques for assessing cellular mechanical parameters highlights the significance of our methodology in enabling reliable individual-cell mechanical measurements. This study contributes to advancing the field by introducing a robust and versatile methodology for assessing cellular mechanics, with broad implications for cell biology research and biomedical applications.