StepFun: Step 3.5 Flash
The StepFun: Step 3.5 Flash is a text-based AI model developed by stepfun. It can handle context lengths of up to 262144 tokens and supports input in the form of text. Additionally, it provides tools for users and claims to support reasoning capabilities. Considering its pricing structure, this model may be worth shortlisting for those looking for a balance between cost and performance. With an input price per million tokens (MTOK) of $0.1 and an output price per MTOK of $0.3, it is positioned in the middle ground. Its blended benchmark score stands at 26.6 across one independent benchmark; however, more evaluation data would provide a clearer understanding of its capabilities.
Benchmark results
Independent, published benchmarks. Blended score 24.5 across 1 benchmark, last refreshed 2026-10-13. How scoring works →
| Benchmark | Measures | Score |
|---|---|---|
| AI Index | broad capability composite | 28.0 |
- 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 |
Similar models
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.