The ring subsets described were obtained from the ZINC database and used as is. The curves plotted are a result of counting the number of heavy atoms in each compound for the ZINC subset and plotting the number of times a fragment with the corresponding heavy atom count occurs. Predictions were then made using each model and the dataset filtered for those fragments for which templates were predicted and successfully applied. From this we can determine how many compounds in the subset we can predict a one-step retrosynthesis for, and how this varies with ring size for which we have used heavy atom count as a proxy measure. The overlap of each fragment set with the training sets is available in the supporting information (SI_6).