Shipping fees have become a critical friction point in e-commerce, often generating psychological discomfort that can trigger cart abandonment and brand switching. At the same time, retailers increasingly deploy free shipping, free returns, and shipping vouchers as competitive tools to stimulate conversion, loyalty, and impulsive purchases. This narrative review synthesizes recent academic evidence (2021–2026) on free shipping and shipping-fee-related psychological mechanisms, drawing on experimental studies, surveys, qualitative work, and large-scale transaction datasets. Findings suggest that shipping cost perceptions influence decision-making disproportionately relative to the fee amount, frequently interacting with promotional cues (discounts, flash sales, scarcity), interface design, and perceived fairness. Free shipping strategies significantly improve conversion when deployed tactically (e.g., late-stage retargeting), yet may also stimulate impulsive and consumptive behaviour, especially among younger audiences and promotion-sensitive segments. The review concludes with evidence-based managerial recommendations and research implications to support ethical, effective shipping-fee policy design and communication.
Joshi et al. (Sun,) studied this question.