Proportionality is a principle for the allocation of sanctions, requiring commensurability between offense seriousness and sanction severity. For example, no number of trivial offenses warrant a sentence appropriate to a single moderately serious offense. A study selected pairs of offenses and quantified seriousness levels using official statistics. From this, a curve was calibrated as a representation of the cumulation of sentence. This framework offers a better understanding of the principle of proportionality in regard to the multiple offender and has implications for guidance. In addition, it provides a numerical standard against which to investigate whether judicial practice satisfies the principle of proportionality in this type of case. The article acknowledges that the proposed framework is open to the charge of introducing a true precision into sentencing. But it advances a counter charge: when an analysis of a numerical problem is characterized largely by description, there is the risk of a false imprecision. The article states that the reader's agreement with the claim will be evidence of the article's value. Figures, notes, references