  Fault-tolerant quantum computing will require accurate estimates of the
resource overhead, but standard metrics such as gate fidelity and diamond
distance have been shown to be poor predictors of logical performance. We
present a scalable experimental approach based on Pauli error reconstruction to
predict the performance of concatenated codes. Numerical evidence demonstrates
that our method significantly outperforms predictions based on standard error
metrics for various error models, even with limited data. We illustrate how
this method assists in the selection of error correction schemes.
