StepFun: Step 3.5 Flash
This AI model, Step 3.5 Flash, is designed for text-based input and output, with a maximum context length of 262144 tokens. It supports tools and reasoning capabilities. Its pricing structure includes $0.1 per million input tokens and $0.3 per million output tokens, making it a relatively expensive option compared to others. The model's benchmark standing is not exceptional, with a blended score of 33.2 across one independent test. As such, users with very specific needs or those who want a high-end solution may consider shortlisting this model due to its robust tool and reasoning capabilities.
Benchmark results
Independent, published benchmarks. Blended score 33.2 across 1 benchmark, last refreshed 2026-09-07. How scoring works →
| Benchmark | Measures | Score |
|---|---|---|
| AI Index | broad capability composite | 32.2 |
- Model ID
- stepfun/step-3.5-flash
- Vendor
- stepfun
- Released
- January 2026
- Tokenizer
- Other
- Input Modalities
- text
- Output Modalities
- text
- Max Output
- 65,536 tokens
- Tool Calling
- ✓ supported
- Structured Output
- not supported
- Reasoning Mode
- ✓ supported
- Vision
- text only
- Audio
- no
- Moderated
- no
What it costs in practice
Computed from the current $0.10/M input and $0.30/M output rates. Run your own numbers →
| Job | Tokens | Cost |
|---|---|---|
| Summarize a 50-page report | 30k in / 1.5k out | under $0.01 |
| Classify 1,000 customer emails | 500k in / 50k out | $0.07 |
| A month of a busy support chatbot | 5M in / 2M out | $1.10 |
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Quick answers
- How much does StepFun: Step 3.5 Flash cost?
- $0.10 per million input tokens and $0.30 per million output tokens.
- What is StepFun: Step 3.5 Flash's context window?
- 262,144 tokens, roughly 393 pages of text in a single request.
- Does StepFun: Step 3.5 Flash support tool calling?
- It supports tool calling, a reasoning mode.
- Can StepFun: Step 3.5 Flash process images?
- No, it is text-only on the input side.