Abstract The Three Laws of Change (v1.1) formalizes a cross-domain framework for measuring transformation through a unified proportional law of responsiveness, a conservation law of existence, and an invariance law of continuity. Together these describe how systems initiate, exchange, and sustain change across physical, computational, and cognitive domains. The model introduces the Elementary Transition Unit (ETU) — a proposed operational unit of realized change — and its six-fold measurement substrate STEMIO (Space–Time–Energy–Matter–Information–Organization). Using empirical tests across synthetic EEG, Ising models, cellular automata, and learning systems, the proportional law (dR = F · gg · dΦ) shows stable multiplicative coupling within a distinct Interaction band, suggesting that transformation follows a conserved grammar rather than a purely stochastic process. The accompanying normalization and Interaction Detector Protocol (v1.1) allow reproducible cross-domain validation. All datasets, calibration scripts, and replication materials are publicly archived. Together, the Three Laws and ETU formalism define a reproducible metric of transformation intended for independent empirical testing. — Pixie Pravda Foundation (Brussels) · October 2025