A novel, non-invasive, two-phase behavioral assay is introduced to quantify drug craving in rodents, bypassing surgical catheterization. Phenotypic screening of a baseline population (N = 53) via two-bottle choice successfully stratifies rats into Drug-Preferring and Water-Preferring subgroups using an optimized 0.5 mg/mL cocaine concentration. A representative sub-sample is then tested in an apparatus where an adjustable, spring-loaded door acts as a physical analogue to a progressive-ratio schedule. Under increased mechanical resistance (150g to 300g, corresponding to 1.47 to 2.94 Newton, and 0.147 to 0.294 Joule over a 10 cm door displacement), drug- preferring subjects exhibit persistent motivation to re-enter the drug chamber, whereas controls cease crossing. Notably, water-preferring rats actively reject the drug after a brief sip, returning immediately to the neutral water chamber. This refined protocol transforms qualitative profiles into a precise, scalar, and quantitative metric of motivational drive determined by the animal’s internal craving state, maintaining veterinary refinement to attain reduction-refinement-respect, the three Rs towards ANIMAL WELFARE in preclinical research.