Calcium alginate capsules encapsulating bitumen rejuvenator represent an extrinsic asphalt self-healing system characterized by high encapsulation efficiency and the capability for multiple, time-dependent releases of rejuvenator. The core rejuvenator content within these capsules is a critical determinant of their self-healing performance. This study determined and compared the rejuvenator content in calcium alginate capsules using three analytical techniques: solvent extraction, thermogravimetric analysis (TGA), and X-ray computed tomography (X-CT). Capsules were fabricated with various rejuvenator types and shell compositions. The efficiency and accuracy of these methods were systematically evaluated, and an improved TGA-based protocol was developed to address systematic errors present in conventional approaches. Results indicated that both the type of rejuvenator and the shell material density significantly influence core content. The solvent extraction method measured rejuvenator contents of 52.24 % in oil capsules, 27.34 % in aromatic rejuvenator capsules, and 47.61 % in oil capsules with nano-Fe₃O₄. The improved TGA method demonstrated superior accuracy and minimal error, whereas the X-CT method showed substantial discrepancies. Importantly, our findings establish that the improved TGA method is not only more user-friendly and less material-intensive than the extraction method, but also offers a more reliable and practical approach for quantitative assessment of capsule core content, outperforming the other techniques evaluated.