Model Comparison
Step 3.5 Flash 2603
vs. Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback)
Comparing 2 AI models · 0 benchmarks · StepFun, Anthropic
Recommended Pick
StStep 3.5 Flash 26037 metric winsStrongest on: Value, Input price, Output price
Best Value
Step 3.5 Flash 2603
100.0 value score
26.5 reasoning / $0.15/1M
Lowest Price
Step 3.5 Flash 2603
$0.10/1M input price
Best Reasoning
Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback)
64.8 reasoning score
Blends available reasoning benchmarks
Best for Coding
Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback)
80.7 coding index
Differences That Matter
Best value
Step 3.5 Flash 2603 has the strongest quality-to-price mix at 100.0 out of 100 value points.
Price gap
Step 3.5 Flash 2603 is 100x cheaper on input tokens than Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback).
Speed gap
Step 3.5 Flash 2603 generates about 3.1x as many tokens per second as Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback).
Reasoning gap
Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback) leads Step 3.5 Flash 2603 by 38.3 points on reasoning.
Top-pick rationale
Step 3.5 Flash 2603 wins 7 measurable categories, including Value, Input price, Output price, Blended price.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
Step 3.5 Flash 2603
StepFun
TTFT
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Time
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tok/s
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Tokens
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Cost
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Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback)
Anthropic
TTFT
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Time
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tok/s
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Tokens
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Cost
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Which answer was more useful?
Secure AI Chat made in Europe
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OpenAI-compatible inference
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Full Comparison
| Metric | Top Pick St Step 3.5 Flash 2603 | An Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback) |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $0.10/1M | $10.00/1M |
| Output Cost | $0.30/1M | $50.00/1M |
| Blended (3:1) | $0.15/1M | $20.00/1M |
| Specifications | ||
| Organization | StepFun | Anthropic |
| Release Date | Apr 2, 2026 | Sep 1, 2026 |
| Performance & Speed | ||
| Throughput | 209.5 tok/s | 68.5 tok/s |
| TTFT | 1050ms | 130210ms |
| Latency | 10600ms | 130210ms |
| Composite Indices | ||
| Value Score | 100.0 | 1.8 |
| Reasoning Score | 26.5 | 64.8 |
| Intelligence | 26.5 | 64.8 |
| Coding | — | 80.7 |
Key Takeaways
Step 3.5 Flash 2603 offers the best value at $0.10/1M,making it ideal for high-volume applications and cost-conscious projects.
Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback) has the strongest reasoning profile with a 64.8 reasoning score,combining the available reasoning-heavy benchmarks.
Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback) reaches a 80.7 coding index,making it the top choice for software development and code generation tasks.
All models support context windows of ∞+ tokens,suitable for processing lengthy documents and maintaining extended conversations.
When to Choose Each Model
Step 3.5 Flash 2603
- Cost-sensitive applications
- High-volume processing
Claude Fable 5.1 (Adaptive Reasoning, Xhigh Effort, Default Fallback)
- Complex reasoning tasks
- Research & analysis
- Code generation
- Software development
