We consider the fragment of deep inference free of compression mechanisms and compare its proof complexity to other systems, utilising ‘atomic flows’ to examine size of proofs. Results include a simulation of Resolution and dag-like cut-free Gentzen, as well as a separation from bounded-depth Frege.

**NB: ** * There are errors in some statements and proofs of this article that have been amended in the long version, On the relative proof complexity of deep inference via atomic flows.*