Step 3.5 Flash Intelligence, Performance & Price Analysis
Model summary
Intelligence
Artificial Analysis Intelligence Index
Speed
Output tokens per second
Input Price
USD per 1M tokens
Output Price
USD per 1M tokens
Verbosity
Output tokens from Intelligence Index
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
| Reasoning | Yes This page shows the reasoning version of this model. A non-reasoning variant may also exist. |
|---|---|
| Input modality | Supports: text |
| Output modality | Supports: text |
| Context window | 256k ~384 A4 pages of size 12 Arial font |
| Total parameters | 196B |
| Active parameters | 11B Number of parameters active per token during inference |
| License | Apache 2.0 |
| Model weights | Hugging Face |
Step 3.5 Flash is amongst the leading models in intelligence and well priced when comparing to other open weight models of similar size. It's also notably fast, however very verbose. The model supports text input, outputs text, and has a 256k tokens context window.
Step 3.5 Flash scores 38 on the Artificial Analysis Intelligence Index, placing it well above average among comparable models (averaging 27). When evaluating the Intelligence Index, it generated 200M tokens, which is very verbose in comparison to the average of 17M.
Pricing for Step 3.5 Flash is $0.10 per 1M input tokens (competitively priced, average: $0.55) and $0.30 per 1M output tokens (competitively priced, average: $1.70). In total, it cost $74.80 to evaluate Step 3.5 Flash on the Intelligence Index.
At 93 tokens per second, Step 3.5 Flash is notably fast (55).
Intelligence
Artificial Analysis Intelligence Index
Artificial Analysis Intelligence Index by Open Weights / Proprietary
Intelligence Evaluations
Openness
Artificial Analysis Openness Index: Results
Intelligence Index Comparisons
Intelligence vs. Price
Intelligence Index Token Use & Cost
Output Tokens Used to Run Artificial Analysis Intelligence Index
Cost to Run Artificial Analysis Intelligence Index
Context Window
Context Window
Pricing
Pricing: Input and Output Prices
Intelligence vs. Price (Log Scale)
Pricing Comparison of Step 3.5 Flash API Providers
Speed
Measured by Output Speed (tokens per second)
Output Speed
Output Speed vs. Price
Latency
Measured by Time (seconds) to First Token
Latency: Time To First Answer Token
End-to-End Response Time
Seconds to output 500 Tokens, calculated based on time to first token, 'thinking' time for reasoning models, and output speed
End-to-End Response Time
Model Size (Open Weights Models Only)
Model Size: Total and Active Parameters
Frequently Asked Questions
Common questions about Step 3.5 Flash
Step 3.5 Flash was released on February 2, 2026.
Step 3.5 Flash was created by StepFun.
Step 3.5 Flash scores 38 on the Artificial Analysis Intelligence Index, placing it well above average among other open weight models of similar size (median: 27).
Step 3.5 Flash generates output at 92.6 tokens per second (based on StepFun's API), which is well above average compared to other open weight models of similar size (median: 55.0 t/s).
Step 3.5 Flash has a time to first token (TTFT) of 2.86s (based on StepFun's API), which is at the higher end compared to other open weight models of similar size (median: 2.24s).
Step 3.5 Flash costs $0.10 per 1M input tokens (very competitive, median: $0.60) and $0.30 per 1M output tokens (very competitive, median: $2.20), based on StepFun's API.
Step 3.5 Flash costs $0.10 per 1M input tokens and $0.30 per 1M output tokens (based on StepFun's API). For a blended rate (3:1 input to output ratio), this is $0.15 per 1M tokens. Pricing may vary by provider. Compare provider pricing
When evaluated on the Intelligence Index, Step 3.5 Flash generated 200M output tokens, which is at the higher end compared to other open weight models of similar size (median: 17M).
Yes, Step 3.5 Flash is a reasoning model. It uses extended thinking or chain-of-thought reasoning to work through complex problems before providing an answer.
Step 3.5 Flash supports text input.
Step 3.5 Flash supports text output.
No, Step 3.5 Flash does not support image input. It can only process text.
No, Step 3.5 Flash is not multimodal. It only supports text input.
Step 3.5 Flash has a context window of 260k tokens. This determines how much text and conversation history the model can process in a single request.
Yes, Step 3.5 Flash is open weights. The model weights are publicly available and can be downloaded for self-hosting.
Step 3.5 Flash has 196 billion parameters (11 billion active).
Step 3.5 Flash is a Mixture of Experts (MoE) model with 196 billion total parameters, but only 11 billion active parameters are used during inference.
Step 3.5 Flash is released under the Apache 2.0 license. This license allows commercial use. View license
Step 3.5 Flash achieves a score of 38 on the Artificial Analysis Intelligence Index. This composite benchmark evaluates models across reasoning, knowledge, mathematics, and coding.
Yes, Step 3.5 Flash is available via API through 2 providers. Compare API providers
Step 3.5 Flash is available through 2 API providers. Compare providers