Quantitative research on how grandparents fare when looking after grandchildren has mainly focused on general wellbeing indicators, showing that grandparenting is linked to higher wellbeing. However, global assessments of wellbeing reveal little about activity-specific experiences and only indirectly provide insights about how grandparents experience grandchild care. Whereas qualitative studies have observed diversity in grandparenting experiences, quantitative insights regarding potential strains of grandparenting are scarce. This study examines directly to what extent grandparents experience supplementary grandchild care as burdensome and obligatory, and tests – building on role strain theory – how differences in grandparents’ characteristics can explain these experiences. Analyses are based on data collected in 2015 and 2018 among 3,429 Dutch grandparents who look after grandchildren. Descriptive findings show that 20 per cent of the studied grandparents experienced grandparenting as fairly/very burdensome and 8 per cent as fairly/very obligatory. Ordinal logistic regression models with random effects show that more-intense grandparenting situations were linked to higher levels of burden and obligation. Moreover, grandparents in poor health, higher education and those with other responsibilities (e.g. paid work) were relatively more likely to experience higher levels of burden and obligation. Our findings imply that the understanding of non-custodial grandparenting as only rewarding might be one-sided, as positive and negative experiences can go together. There appears to be substantial heterogeneity in how grandparents experience looking after their grandchildren.