The "magnitude effect" refers to the phenomenon where stimuli of greater magnitude appear to last longer in duration. Previous studies have explored this effect among children using various duration assessment tasks, but the findings have been inconsistent. Moreover, no replication studies have been conducted on this topic among children thus far. The simultaneous duration assessment task, which is one method for investigating time perception, has been used only twice in children and produced the magnitude effect. Thus, we aimed to replicate these findings and validate them through an additional replicated study. For these aims, we recruited 45 Arab-speaking children aged 7–12 to participate in two studies. In Study 1, they were asked to perform a simultaneous duration assessment task, where they had to assess the illumination durations of lightbulbs with strong and weak intensities simultaneously. In Study 2, they were asked to perform a duration reproduction task, where they had to reproduce the durations of illumination of the same stimuli. Both studies found a magnitude effect pattern, where the children tended to report that the lightbulb with the stronger intensity was illuminated for a longer duration or had a strong tendency to not choose the lightbulb with the weaker intensity. These results are discussed in terms of possible explanations for the conflicting results found in previous literature, as well as their consistency with the pacemaker model’s explanation for the effect.