Past research has shown that performance in ordinal magnitude tasks is enhanced when stimuli are presented in ascending order, suggesting that magnitude is mapped to temporal order, with small magnitude associated with early and large with late presentation. The present study addresses the automaticity of this effect and its limitations. We used the “same/different” task for numbers (Experiment 1) and physical sizes of shapes (Experiment 2) as well as identity of shapes (Experiment 3). The advantage for stimuli in ascending order was found for both numbers and physical sizes of shapes. However, it was limited to specific conditions – when magnitude processing was required for the task and when a “different” response was mapped to the right hand side. Thus, it seems that the automatic mapping of magnitude to temporal order is dependent on the mapping of magnitude to space.