Methods and systems to summarize a source text as a function of contextual information, including to fit a summary within a context-based allotted time. The context-based allotted time may be apportioned amongst multiple portions of the source text, such as by relevance. The context-based allotted time and/or relevance may be user-specified and/or determined, such as by look-up, rule, computation, inference, and/or machine learning. During summary presentation, one or more portions of the source text may be re-summarized, such as to adjust a level of detail. A presentation rate may be user-controllable. Where new and/or changed contextual information affects an available time to review a remaining portion of the summary, the summary presentation may be automatically adjusted, and/or one or more portions of the source text may be re-summarized based on a revised context-based allotted time.