The Global Biodiversity Framework adopted at the United Nations Biodiversity Conference set a target to protect 30 percent of the world’s land and sea areas by 2030. This paper evaluates the potential contribution of the 30x30 initiative to biodiversity conservation by examining its implications for species that are endemic or occupy very small habitats. Using more than 600,000 species occurrence maps derived from Global Biodiversity Information Facility data―substantially expanding representation for plants and invertebrates―the study develops high-resolution, country-specific templates that identify priority-ordered protected areas optimized for cost-effective species coverage. Each iteration expands protection to maximize gains for unprotected species until full coverage is achieved, allowing flexibility to adapt to national economic and political constraints, including the 30 percent target of 30x30. The results include priority-ordered terrestrial protected areas for 138 countries and marine protected areas for 160 countries. At the global level, full protection of currently protected species aligns with 30 percent terrestrial and marine coverage. Expanding global land protection from 14.8 to 18.0 percent and marine protection from 16.6 to 19.9 percent would achieve 100 percent species coverage in the database. However, uneven species distributions make this infeasible for all countries within the 30 percent territorial limit. Among the 242,414 critical species analyzed, 65.5 percent are currently protected. Most of the remainder could be covered within national 30 percent limits, although some countries would need to exceed them. The analysis highlights opportunity-cost disparities―particularly for low-income countries―indicating that effective implementation of 30x30 will require international compensation mechanisms. The study underscores that true success lies in species protection rather than territorial extent.