BackgroundWhile e-cigarettes have been identified as an effective means of tobacco harm reduction, the degree to which these devices will realise their harm reduction potential will be determined in large part by how available these products are to adults who smoke. One of the key factors determining that availability is the regulatory regime around these products. Within the US e-cigarettes have become the most commonly used tobacco product by middle and high school students, with disposable e-cigarettes now the most popular type of device used by youth. In this paper, we report data on the prevalence with which one of the most popular disposable e-cigarettes within the US is being used by youth (aged 13–17) and underage young adults (aged 18–20).MethodsA cross-sectional online survey of a probability-based sample of 1215 youth (13–17 years) recruited via Ipsos’ KnowledgePanel and 3370 young adults aged 18–24, among whom 1125 were aged 18–20, recruited via Ipsos’ KnowledgePanel and online consumer research panels.ResultsAmong youth, 3.50% (95% CI: 2.46–4.83) reported smoking combustible cigarettes in the past 30 days, and 6.73% (95% CI: 5.26–8.48) reported using an e-cigarette in the past 30 days. Among underage young adults, 7.22% (95% CI: 5.24–9.67) reported smoking combustible cigarettes every day or some days, and 15.90% (95% CI: 12.96–19.21) reported using e-cigarettes every day or some days. Despite the scale of e-cigarette use in general among the US youth, only 0.04% (95% CI: 0.00–0.38) of 13–17 years old reported using the BIDI® Stick disposable e-cigarette in the past 30 days.ConclusionsWhile disposable e-cigarettes have become the most popular type of e-cigarette used by the US youth, it is likely that the prevalence of use of individual devices varies significantly. There is a need to regularly monitor the use of e-cigarettes by type of device and brand, in order to determine which products have the greatest potential to reduce smoking-related harm among adults who smoke and which products are being used by youth and underage young adults.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12954-023-00820-y.