Model Comparison
Solar Pro 4
vs. Step 3.5 Flash 2603
Comparing 2 AI models · 7 benchmarks · Upstage, StepFun
Recommended Pick
UpSolar Pro 47 metric winsStrongest on: Throughput, Reasoning, Intelligence
Best Value
Step 3.5 Flash 2603
100.0 value score
44.5 reasoning / $0.15/1M
Lowest Price
Step 3.5 Flash 2603
$0.10/1M input price
Best Reasoning
Solar Pro 4
53.3 reasoning score
Blends available reasoning benchmarks
Best for Coding
Solar Pro 4
52.7 coding index
Composite Indices
Higher is better; speed and price are normalized
Standard Benchmarks
Only benchmarks with data are shown
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 3.0x cheaper on input tokens than Solar Pro 4.
Reasoning gap
Solar Pro 4 leads Step 3.5 Flash 2603 by 8.8 points on reasoning.
Top-pick rationale
Solar Pro 4 wins 7 measurable categories, including Throughput, Reasoning, Intelligence, GPQA.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
Solar Pro 4
Upstage
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
Step 3.5 Flash 2603
StepFun
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
Which answer was more useful?
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Full Comparison
| Metric | Top Pick Up Solar Pro 4 | St Step 3.5 Flash 2603 |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $0.30/1M | $0.10/1M |
| Output Cost | $1.20/1M | $0.30/1M |
| Blended (3:1) | $0.52/1M | $0.15/1M |
| Specifications | ||
| Organization | Upstage | StepFun |
| Release Date | Aug 6, 2026 | Apr 2, 2026 |
| Performance & Speed | ||
| Throughput | 66.3 tok/s | — |
| TTFT | 1239ms | — |
| Latency | 31422ms | — |
| Composite Indices | ||
| Value Score | 34.2 | 100.0 |
| Reasoning Score | 53.3 | 44.5 |
| Intelligence | 41.6 | 26.5 |
| Coding | 52.7 | — |
| Standard Benchmarks | ||
| GPQA | 89.1% | 82.6% |
| HLE | 29.2% | 24.5% |
| SciCode | 43.6% | 38.5% |
| LCR | 70.7% | 60.3% |
| IFBench | — | 66.5% |
| TAU-bench v2 | — | 87.4% |
| TerminalBench Hard | — | 32.6% |
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.
Solar Pro 4 has the strongest reasoning profile with a 53.3 reasoning score,combining the available reasoning-heavy benchmarks.
Solar Pro 4 reaches a 52.7 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
Solar Pro 4
- Complex reasoning tasks
- Research & analysis
- Code generation
- Software development
Step 3.5 Flash 2603
- Cost-sensitive applications
- High-volume processing
