Sonnet 5.5 writes the easiest-to-read prose we’ve measured. A whole draft is a different story. Across our writing tests, its average reading grade level was 6.9—just under seventh grade. At medium effort, the comparison was: • Sonnet 5.5: 7.12 • Opus 5.5: 7.28 • GPT-6 Sol: 7.71 • Luna: 8.01 Lower is easier to read. We tested six writing tasks, with three runs at each effort setting. The formulas measure sentence length and word complexity, not whether an argument makes…