Stepfun Step 5 Preview (LLM): On AA Pareto frontier

StepFun released Step 5 Preview on September 18, 2026, a reasoning model that scores 44 on the Artificial Analysis Intelligence Index, well above the median of 25 for comparable models. Step 5 Preview accepts text and image input, outputs text, has a 1M-token context window, and is priced at $1.00 per 1M input tokens and $2.70 per 1M output tokens, versus medians of $1.88 and $10.00. Evaluating the model on the Intelligence Index cost $918.34 and generated 160M tokens, compared with a median of 90M.

Step 5 Preview Intelligence, Performance & Price Analysis Model summary Speed Step 5 Preview is amongst the leading models in intelligence and well priced when comparing to other models of similar price. The model supports text and image input, outputs text, and has a 1M tokens context window. Step 5 Preview scores 44 on the Artificial Analysis Intelligence Index, placing it well above average among comparable models median: 25 . When evaluating the Intelligence Index, it generated 160M tokens, which is very verbose in comparison to the median of 90M. Pricing for Step 5 Preview is $1.00 per 1M input tokens competitively priced, median: $1.88 and $2.70 per 1M output tokens competitively priced, median: $10.00 . In total, it cost $918.34 to evaluate Step 5 Preview on the Intelligence Index. | Reasoning | Yes This page shows the reasoning version of this model. A non-reasoning variant may also exist. | |---|---| | Input modality | Supports: text and image | | Output modality | Supports: text | | Context window | 1M ~1500 A4 pages of size 12 Arial font | Metrics are compared against models of the same class: - Non-reasoning models → compared only with other non-reasoning models - Reasoning models → compared across both reasoning and non-reasoning - Open weights models → compared only with other open weights models of the same size class: - Tiny: ≤4B parameters - Small: 4B–40B parameters - Medium: 40B–150B parameters - Large: 150B parameters - Proprietary models → compared across proprietary and open weights models of the same price range, using a blended 3:1 input/output price ratio: - <$0.15 per 1M tokens - $0.15–$1 per 1M tokens - $1 per 1M tokens Highlights Speed IntelligenceUpdated Artificial Analysis Intelligence Index https://artificialanalysis.ai/evaluations/artificial-analysis-intelligence-index Artificial Analysis Intelligence Index by Open Weights / Proprietary Measures the performance of models on specific capabilities and industries Artificial Analysis Finance & Accounting Index https://artificialanalysis.ai/models/capabilities/finance-and-accounting Intelligence Evaluations Agentic knowledge work, Elo-500 /2000 Agentic real-world work tasks, Elo-500 /2000 AutomationBench-AA https://artificialanalysis.ai/evaluations/automationbench-aa Updated Agentic SaaS workflows Agentic coding & terminal use Coding Reasoning & knowledge GDP.pdf https://artificialanalysis.ai/evaluations/gdp-pdf New Professional document reasoning, All-pass Physics reasoning Knowledge 1 - hallucination rate Long context reasoning Legal agentic work, criterion pass rate Agentic business operations Quantitative analysis on spreadsheets & documents Agentic tool use Kubernetes incident root-cause analysis Visual reasoning MLCR-AA https://artificialanalysis.ai/evaluations/mlcr-aa New Medical long context reasoning AA-Briefcase AA-Briefcase Elo AA-Omniscience AA-Omniscience Index Intelligence Index Comparisons Intelligence Index vs. Cost per Intelligence Index Task Token Use Output Tokens per Intelligence Index Task Cost Cost per Intelligence Index Task Cost to Run Artificial Analysis Intelligence Index Pricing: Cache Hit, Input, and Output Context Window Context Window Frequently Asked Questions Common questions about Step 5 Preview Step 5 Preview was released on September 18, 2026. Step 5 Preview was created by StepFun. Step 5 Preview scores 44 on the Artificial Analysis Intelligence Index, placing it well above average among other reasoning models in a similar price tier median: 25 . Step 5 Preview costs $1.00 per 1M input tokens very competitive, median: $1.88 and $2.70 per 1M output tokens very competitive, median: $10.00 , based on StepFun's API. Step 5 Preview costs $1.00 per 1M input tokens and $2.70 per 1M output tokens based on StepFun's API . For a blended rate 7:2:1 cache hit/input/output ratio , this is $0.51 per 1M tokens. Pricing may vary by provider. Compare provider pricing https://artificialanalysis.ai/models/step-5/providers When evaluated on the Intelligence Index, Step 5 Preview generated 160M output tokens, which is at the higher end compared to other reasoning models in a similar price tier median: 90M . Yes, Step 5 Preview is a reasoning model. It uses extended thinking or chain-of-thought reasoning to work through complex problems before providing an answer. Step 5 Preview supports text and image input. Step 5 Preview supports text output. Yes, Step 5 Preview supports image input and can analyze, describe, and answer questions about images. Yes, Step 5 Preview is multimodal. It can process text and image input and generate text output. Step 5 Preview has a context window of 1.0M tokens. This determines how much text and conversation history the model can process in a single request. No, Step 5 Preview is proprietary. The model weights are not publicly available. Step 5 Preview has 600 billion parameters. Step 5 Preview achieves a score of 44 on the Artificial Analysis Intelligence Index. This composite benchmark evaluates models across reasoning, knowledge, mathematics, and coding. Yes, Step 5 Preview is available via API through 1 provider. Compare API providers https://artificialanalysis.ai/models/step-5/providers Step 5 Preview is available through 1 API provider. Compare providers https://artificialanalysis.ai/models/step-5/providers