Evidence for associations between spatial skills and mathematics has led to the argument that spatial visualization plays a role in mathematical calculation. However, there is no single accepted definition of what spatial visualization encompasses. Here, we investigated spatial visualization in the context of a mental imagery framework. We applied a component model of mental imagery, involving image generation, image maintenance, image transformation (measured using mental rotation), and image scanning, to determine associations between each component and mathematical calculation ability in primary school children (N = 92, age 6-11 years). We found that, after accounting for age, only mental rotation explained significant variation in mathematical calculation. Our findings advance theoretical understanding by demonstrating that spatial visualization definitions, applied to mathematics, should be refined to focus on transformation. This highlights the practical implication that transformation strategies are promising targets for future intervention work, rather than broad visualization strategies.