Social media use research remains dominated by self-report measures, despite concerns they may not accurately reflect objective social media use. The association between commonly employed self-report measures and objective social media use remains unclear. The aim of this study was to determine the degree of association between an objective and commonly employed subjective measures of social media use. The study specifically examined a single-estimate self-report measure, a problematic social media use scale, and objective use derived from smartphone data, in a sample of 209 individuals. The findings showed a very weak non-significant relationship between the objective measure and the single-estimate measure, (r = −.04, p = .58, BF10 = 0.18), and a weak significant relationship between the objective measure and the problematic social media use scale (r = .19, p = .01, BF10 = 3.04). These findings converge with other recent research to suggest there is very little shared variance between subjective estimates of social media use and objective use. This highlights the possibility that subjective social media use may be largely unrelated to objective use, which has implications for ensuring the rigor of future research and raising potential concerns regarding the veracity of previous research. •There is an overreliance on self-report measures of social media in research.•There was no relationship between single estimate self-report social media use and actual social media use.•There was a weak relationship between scores on a problematic social media use scale and actual use.