Duration-based measures of happiness from retrospectively constructed daily diaries are gaining in popularity in population-based studies of the hedonic experience. Yet experimental evidence suggests that perceptions of duration – how long an event lasts – are influenced by individuals' emotional experiences during the event. An important remaining question is whether observational measures of duration outside the laboratory setting, where the events under study are engaged in voluntarily, may be similarly affected, and if so, for which emotions are duration biases a potential concern. This study assesses how duration and emotions co-vary using retrospective, 24-hour diaries from a national sample of older couples. Data are from the Disability and Use of Time (DUST) supplement to the nationally representative U.S. Panel Study of Income Dynamics. We find that experienced wellbeing (positive, negative emotion) and activity duration are inversely associated. Specific positive emotions (happy, calm) are not associated with duration, but all measures of negative wellbeing considered here (frustrated, worried, sad, tired, and pain) have positive correlations (ranging from 0.04 to 0.08; p<.05). However, only frustration remains correlated with duration after controlling for respondent, activity and day-related characteristics (0.06, p<.01). The correlation translates into a potentially upward biased estimate of duration of up to 10 minutes (20%) for very frustrating activities. We conclude that estimates of time spent feeling happy yesterday generated from diary data are unlikely to be biased but more research is needed on the link between duration estimation and feelings of frustration.