The Slop Index Launches: Benchmarking Which AI Models Sound the Least Like AI

The Slop Index, a new evaluation benchmark, has officially launched to measure the gap between the writing styles of 58 frontier large language models and authentic human expression using quantitative metrics and blind human evaluations. Completely avoiding LLM-as-a-judge methodologies, it compares model-generated text against pre-2022 human workplace emails, tweets, and articles. The benchmark calculates a divergence score from 0 to 100 based on blind human votes (40%), along with conciseness, formulaic phrasing, cadence, and typical AI sentence structures (15% each).