<p>Measures of interdisciplinarity are often used to analyse research bibliometrically, yet little is known about whether these indicators capture how researchers themselves perceive interdisciplinarity. Against this background, the objective of this paper is to compare bibliometrically constructed indexes of interdisciplinarity with authors’ self-assessments of the interdisciplinarity of their own papers, thereby providing knowledge into how well these indicators correspond with researchers’ own perceptions. The bibliometric interdisciplinarity measures analyzed include the Shannon entropy, ^<i>2</i><i>D</i>^<i>S</i>, and DIV* indicators. The data analyzed in the study are derived from two separate questionnaire surveys, in which authors were asked about specific articles they had published. In total, the dataset consisted of more than 3300 articles, spanning all fields from the Humanities and Social sciences to the Natural sciences and Engineering. At the level of individual publications, bibliometric indicators often do not correspond with authors’ own assessments of interdisciplinarity. Although all analysed interdisciplinarity indicators show a statistically significant association with author assessments, the relationships are weak: correlation coefficient (Spearman’s rho) for the three bibliometric interdisciplinarity measures ranged from 0.130 to 0.175, highlighting the need for caution when relying solely on such measures for assessing research.</p>