BACKGROUND: Heated tobacco products (HTPs) expanded rapidly after 2014; yet globally, comparable estimates of the number of HTP users remain limited. National surveys rarely include standardized HTP measures, and international surveillance systems do not provide harmonized global user counts.

OBJECTIVE: The aim of the study is to construct a reproducible annual global time series of HTP user estimates for 2014-2024 using publicly available manufacturer disclosures, quantify uncertainty, and compare these estimates with user counts derived from nationally representative survey prevalence data where available.

METHODS: We compiled annual HTP user counts and heated-tobacco stick shipment volumes from publicly available reports of major transnational tobacco companies. In the primary series, we used company-reported user counts when available. For company-year observations without reported user counts, we estimated user numbers by converting reported shipment volumes into implied user counts, applying brand-specific assumptions on average daily consumption per user. As an alternative sensitivity analysis, all company user counts were excluded, and all shipments were converted using a common literature-based consumption parameter. As a complementary check, nationally representative current-use prevalence data from 35 countries were converted to user counts.

RESULTS: Global HTP users reached 48.9 million in 2024 in the primary series (range 45.6-52.1 million). The shipment-only series showed higher totals (67.9 million; range 59.7-78.7 million). Survey-based estimates yielded 21.8 million users across 35 countries, reflecting partial geographic coverage.

CONCLUSIONS: A transparent, updateable global time series documents rapid HTP growth from 2014 to 2024, with 2024 totals ranging from 45.6 to 78.7 million users depending on the estimation approach. As standardized HTP measures are incorporated into national surveys, future estimates can be refined, and uncertainty reduced.