Model Comparison
Solar Pro 2 (Preview) (Reasoning)
vs. Step 3.5 Flash
Comparing 2 AI models · 0 benchmarks · Upstage, StepFun
Recommended Pick
StStep 3.5 Flash2 metric winsStrongest on: Reasoning, Intelligence
Lowest Price
Step 3.5 Flash
$0.10/1M input price
Best Reasoning
Step 3.5 Flash
26.0 reasoning score
Blends available reasoning benchmarks
Differences That Matter
Reasoning gap
Step 3.5 Flash leads Solar Pro 2 (Preview) (Reasoning) by 13.5 points on reasoning.
Top-pick rationale
Step 3.5 Flash wins 2 measurable categories, including Reasoning, Intelligence.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
Solar Pro 2 (Preview) (Reasoning)
Upstage
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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Step 3.5 Flash
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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Which answer was more useful?
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OpenAI-compatible inference
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Full Comparison
| Metric | Up Solar Pro 2 (Preview) (Reasoning) | Top Pick St Step 3.5 Flash |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | — | $0.10/1M |
| Output Cost | — | $0.30/1M |
| Blended (3:1) | — | $0.15/1M |
| Specifications | ||
| Organization | Upstage | StepFun |
| Release Date | May 20, 2025 | Feb 2, 2026 |
| Performance & Speed | ||
| Throughput | — | 214.0 tok/s |
| TTFT | — | 1050ms |
| Latency | — | 10400ms |
| Composite Indices | ||
| Value Score | — | 100.0 |
| Reasoning Score | 12.5 | 26.0 |
| Intelligence | 12.5 | 26.0 |
Key Takeaways
Step 3.5 Flash offers the best value at $0.10/1M,making it ideal for high-volume applications and cost-conscious projects.
Step 3.5 Flash has the strongest reasoning profile with a 26.0 reasoning score,combining the available reasoning-heavy benchmarks.
All models support context windows of ∞+ tokens,suitable for processing lengthy documents and maintaining extended conversations.
When to Choose Each Model
Solar Pro 2 (Preview) (Reasoning)
- General-purpose AI
- Versatile applications
Step 3.5 Flash
- Cost-sensitive applications
- High-volume processing
- Complex reasoning tasks
- Research & analysis
