Mathematical abilities and (pre)skills are based on non-symbolic and symbolic systems of numerical processing. The aim of this study was to investigate quantity processing in preschool children in Croatia. A total of 122 typically developing preschool children (two equal groups; four- and five-year-olds) were solving two types of tasks: non-symbolic and symbolic quantity estimations. Contrary to our expectations, the children’s performances on non-symbolic and symbolic tasks were not statistically significantly connected. As we had assumed, both groups performed better on the non-symbolic tasks, and the older group outperformed the younger group on both types of tasks. We found distance effect on the non-symbolic task and size effect on the symbolic task for both groups. The results are consistent with the findings of previous research supporting the developmental perspective of two systems and the role of formal educational in their progression.