Artificial Analysis tested StepFun’s new Step 5 Preview model against the rest of the field and put it at 44 on its Intelligence Index, the same score it gives Moonshot AI’s Kimi K3 (max). The research firm says Step 5 Preview reaches that mark for roughly 2.8 times less cost per task, based on its own benchmark runs shared in a thread on X. Step 5 Preview is a mixture of experts model with 600 billion total parameters and 27 billion active per pass, according to the same testing. Artificial Analysis reports the model trails top peers specifically on agentic evaluations, the tasks that measure how well a system plans and executes multi step work rather than answer single questions. StepFun, a Chinese lab, has not published its own benchmark numbers to compare against the independent test. For teams pricing inference against Kimi K3, Step 5 Preview’s cost profile is worth a bake off before the next contract renews.
Artificial Analysis reported the comparison in a thread on X on September 22, 2026.
