Knowledge of derivational affixes makes an important contribution to second language learners' success when reading. Yet while the effects of some learner variables (L2 proficiency, L1 background) have been investigated, there has been little research addressing the effects of varying characteristics of affixes on their acquisition. The goal of this study was to develop a range of metrics concerning the characteristics of derivational affixes with respect to their frequency of occurrence, semantic salience, and orthographic and phonological form. The study presents 19 metrics (58 when including variants) for 38 derivational affixes (12 prefixes; 26 suffixes) with a range of frequencies. Each metric is calculated across progressively larger vocabulary size levels in recognition of the fact that as learners' vocabulary knowledge develops, their exposure to and knowledge of words including derivational affixes grows. Examples of a selection of metrics for one affix are provided (the full data set being available online; https://osf.io/2vcg9/) as well as some global observations on the data set. It is hoped that these metrics will allow future analyses that provide insights into the process of L2 derivational affix acquisition (by exploring which metrics and to what degree the metrics contribute to acquisition) as well as insights into the order in which affixes are learnt and at what stage in L2 development different affixes are acquired.