The Isoperimetric Baseline: A Unified Metric for the Perimeter of an Ellipse This paper presents a novel geometric framework for resolving the elliptical perimeter problem by identifying a foundational constant, the Isoperimetric Baseline (n0≈1.5349). While traditional methods rely on infinite series or heuristic approximations, this research normalizes the circle into a p-norm (superellipse) framework to establish a point of parity where curve length equals the bounding box. Key Contributions: Derivation of n0: A closed-form derivation of the baseline exponent required for isoperimetric parity. Lambert-Divergent Metric: An original metric utilizing the Lambert W function to model curvature redistribution across all eccentricities. Computational Verification: Includes a reference Python implementation (Appendix B) demonstrating superior precision and theoretical residuals as low as 10−25.