Physical activity provides essential information to assess general health and evaluate the outcome of interventions. However, evaluation of physical activity necessitates reference values for comparison. The current study aimed to present reference values for accelerometer-based data on physical activity in a background population. We conducted a population-based cross-sectional study using accelerometer-based data on physical activity and self-reported data on demographics and health from a cohort of randomly selected individuals of 18–80 years of age registered in the Danish Civil Registration System (CRS) (n = 242). Participants took an average of 6095 daily steps, had an average cadence of 98.5, spent 3.7 h standing, 1.4 h walking, 3.8 min cycling, 7.0 h in sedentary activities, and had 43 sit to stand transfers. The results varied when examining sex and individual age groups. Our findings are important to clinical practice and research, as they provide sex- and age-specific reference values to enable comparison of daily physical activity levels.