Title: On the Predictability of Pruning Across Scales. Abstract: We show that the error of iteratively-pruned networks empirically follows a scaling law with interpretable coefficients that depend on the architecture and task. We functionally approximate the error of the pruned networks, showing that it is predictable in terms of an invariant tying width, depth, and pruning level, such that networks of vastly different sparsities are freely interchangeable. We demonstrate the accuracy of this functional approximation over scales spanning orders of magnitude in depth, width, dataset size, and sparsity. We show that the scaling law functional form holds (generalizes) for large scale data (CIFAR-10, ImageNet), architectures (ResNets, VGGs) and iterative pruning algorithms (IMP, SynFlow). As neural networks become ever larger and more expensive to train, our findings suggest a framework for reasoning conceptually and analytically about pruning.