ObjectivesChallenges in estimating total whole grain intake have led to the use of surrogate estimates, of which accuracy has not been assessed. We examined the suitability of five potential surrogates (dietary fiber; bread; rye bread; rye, oat and barley combined; rye) and a whole grain food definition to measure total whole grain intake in the Finnish adult population.MethodsOur data comprised 5094 Finnish adults participating in the national FinHealth 2017 Study. Dietary intake was assessed by a validated FFQ. Food and nutrient intakes, including total whole grain, were calculated utilizing the Finnish Food Composition Database. The Healthgrain Forum whole grain food definition was applied to examine definition-based whole grain intake. Spearman correlations and quintile cross-classifications were calculated.ResultsDefinition-based whole grain intake and consumption of rye, oat and barley combined had consistently the strongest correspondence with total whole grain intake. Rye and rye bread consumption also corresponded well with total whole grain intake. The correspondences of dietary fiber and bread with total whole grain were lower and more affected by the exclusion of energy under-reporters. Furthermore, their correlations with total whole grain intake varied the most between population subgroups.ConclusionsRye-based estimates, especially rye, oat and barley combined, and definition-based whole grain intake appeared suitable surrogate estimates of total whole grain intake for epidemiological research of Finnish adults. The variation between surrogate estimates in their correspondence with total whole grain intake demonstrated the need for further evaluation of their accuracy in different populations and regarding specific health outcomes.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00394-023-03119-7.