<p>In frequency-based cable tension identification, it is common to neglect either bending stiffness or sag to avoid repetitive solutions to transcendental equations or optimization problems for each cable. For rigid cables, bending stiffness cannot be neglected; for long cables using non-contact methods, measuring in-plane frequencies potentially influenced by non-negligible sag is necessary. However, this absence of a clearly delineated theoretical scope for the model’s simplification fosters both empiricism and inconsistency in the methodology. To address these issues, this paper proposes a unified algorithm that is applicable to the parameter identification of both rigid short cables and sagged long cables. A temporal and spatial scaling approach is employed to simplify the dynamic equations of sagged rigid cables, yielding a general frequency equation and corresponding numerical solution for the dimensionless frequency within a parameter space defined by sag and dimensionless cable length. Based on this universal solution and the reciprocal relationship of frequency ratio, a unified algorithm is presented. Using any three measured frequencies, the algorithm can determine the Irvine parameter and any two unknown parameters of cable tension, bending stiffness, and mass density through simple interpolation, thereby eliminating the need for complex calculations such as iterative solutions or equation-solving. Furthermore, a sensitivity analysis is conducted to quantify the robustness of the identified parameters against frequency perturbations. The reliability and accuracy of the proposed method are validated through comparisons with laboratory experiments, real-life bridge cable data from various references, and a field test.</p>