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The Sustainable Development Goal (SDG) Indicator 11.3.1, defined as the ratio of Land Consumption Rate (LCR) to Population Growth Rate (PGR) and collectively referred to as LCRPGR, is widely used to assess urban land use efficiency (LUE). However, its reliance on two-dimensional built-up area data limits its ability to capture vertical urban growth and spatial form. This study introduces a trajectory-based framework that integrates built-up area (BUA) and built-up volume (BUV) to enhance LUE assessments. By representing urban growth as a trajectory in normalized BUA–BUV space, the framework reveals prevailing built form (horizontal, balanced, or vertical) and directional growth patterns (expansion or intensification) that underlie LUE outcomes. We apply the BUA–BUV trajectory framework to 10,856 urban centers using data from the Global Human Settlement Urban Centre Database (GHS-UCDB 2025) spanning 1980–2020. Results show that horizontal expansion remains the globally dominant growth pattern, with 97% of urban centers classified as horizontally dominant in 2020. Typology analysis reveals that “Sustained Horizontal Growth” accounts for most urban trajectories, while typologies indicative of vertical intensification are rare. Although the global median LCRPGR values declined from 1.67 (1980–2000) to 1.05 (2000–2020), suggesting more proportionate land consumption, trajectory distributions show limited structural transition toward vertical or balanced growth. The findings underscore the limitations of relying on LCRPGR alone to assess LUE in the context of urban sustainability. The BUA–BUV trajectory framework complements SDG 11.3.1 by embedding spatial structure into LUE assessment, distinguishing between structurally divergent paths that yield similar LCRPGR values. This added diagnostic capability supports more informed interpretations of urban growth and can guide planning strategies toward compact, balanced, and sustainable development pathways.