As evidence accumulates that even moderate alcohol use carries health risks, policy interest is shifting toward reducing everyday exposure; yet existing spatial metrics still mostly map outlet presence rather than behaviorally plausible purchase opportunities along routine trips. We introduce behaviorally informed, detour-based indices tailored to after-work alcohol acquisitions on walking commutes. Using preference surveys of adults in two German cities, we infer empirical “detour budgets” for after-work alcohol runs and embed them in a home-level index capturing the share of transit–home walking paths that include at least one feasible purchase opportunity, and a store-level leverage index capturing how many such paths each outlet can intercept. Under a 250 m detour budget, roughly the extra distance that half of respondents are willing to walk, half of stop–home walking segments and 29% of homes are exposed on all routes. Kiosks, while only about 28% of outlets, account for roughly 35% of this after-work leverage. Applying the indices to European alcohol-policy regimes, we show that a state retail monopoly cuts mean home exposure by about 75%, while targeted removal of the 25% most exposure-imposing outlets achieves almost the same reduction as a selective licensing pattern that shuts more stores. These findings show how behaviorally informed exposure metrics can support more targeted alcohol-availability policy and be extended to other purchase-chain-specific exposures.