Background and Aims: The hypothesis that study strategies can compensate for less study time in predicting learning outcomes has often been proposed but rarely tested empirically. Methods: In the present study, 231 university students reported their daily perceived time spent on self-study, study strategies (planning, monitoring, concentration and procrastination) and goal achievement over a 30 days period. Results and Conclusion: Results showed that both more overall perceived study time and better study strategies (better planning, monitoring, and concentration, less procrastination) predicted higher goal achievement at the end of the day. In addition, perceived study time and study strategies interactively predicted goal achievement. When students reported better planning, monitoring and concentration as well as lower procrastination, less time was needed to achieve a high goal level compared to days on which they studied less strategically. In other words, when students studied less strategically, they had to invest more time to reach a higher goal level. In addition, perceived study time and study strategies were related to students' negative affect. Negative affect was particularly high when students studied for many hours with low concentration, and it was particularly low when students studied for only a few hours and procrastinated less. Taken together, the results suggest a compensatory effect of study time and study strategies on daily goal achievement and affect, highlighting the need to teach students effective study strategies.