Complexity poses a significant challenge for big history because it is a central theme within the field, which organizes history into cosmological periods based on the sequential emergence of qualitatively distinct forms of complexity. How can big historians identify and differentiate distinct thresholds of emergent complexity while unifying the entire sequence under a single metric that illustrates the increase of complexity across various magnitudes and distinct forms? The use of a cosmic distance ladder by cosmologists suggests a similar approach for complexity: a complexity ladder for big history. While this paper does not establish a complexity ladder, it outlines the necessary framework for one and examines the relationship between a complexity ladder and chronological periodization.