Under the United Nations’ Agenda 2030, one indicator of progress towards the conservation of mountain ecosystems including their biodiversity (SDG 15.4) is the percentage [%] coverage of important sites for mountain biodiversity key biodiversity areas, KBAs) by protected areas (PAs) (SDG 15.4.1). KBAs are areas that contribute significantly to the persistence of global biodiversity. Currently, the indicator is hosted by the UN Environment Programme World Conservation Monitoring Centre (WCMC). The indicator is officially calculated as the average of the PA coverage of KBAs within a country that are considered mountainous based on the WCMC mountain definition from 2000. As an alternative, the Global Mountain Biodiversity Assessment (GMBA) calculates the indicator as the ratio between the total area of protected KBAs and the total area of KBAs in mountains, applying its latest mountain definition from 2022. In this one-pager collection, we present the indicator based on the GMBA calculation approach, for both countries and major mountain systems worldwide that have actual overlap of mountains and KBA (190 countries and 267 mountain systems).