Model Comparison
Solar Pro 4
vs. Step 3.5 Flash 2603
Comparing 2 AI models · 0 benchmarks · Upstage, StepFun
Recommended Pick
StStep 3.5 Flash 26036 metric winsStrongest on: Value, Input price, Output price
Best Value
Step 3.5 Flash 2603
100.0 value score
17.0 reasoning / $0.15/1M
Lowest Price
Step 3.5 Flash 2603
$0.10/1M input price
Best Reasoning
Solar Pro 4
28.2 reasoning score
Blends available reasoning benchmarks
Best for Coding
Solar Pro 4
52.7 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 3.0x cheaper on input tokens than Solar Pro 4.
Speed gap
Step 3.5 Flash 2603 generates about 1.7x as many tokens per second as Solar Pro 4.
Reasoning gap
Solar Pro 4 leads Step 3.5 Flash 2603 by 11.2 points on reasoning.
Top-pick rationale
Step 3.5 Flash 2603 wins 6 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.
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?
Secure AI Chat made in Europe
Use Claude, ChatGPT, Gemini alongside with EU-Hosted Models like Deepseek, Qwen & Kimi.
EU-hosted inference
Servers in Germany & Finland. Designed to meet strict GDPR and ISO 27001 compliance requirements.
Full Comparison
| Metric | Up Solar Pro 4 | Top Pick 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 | 82.6 tok/s | 140.1 tok/s |
| TTFT | 2060ms | 3370ms |
| Latency | 26270ms | 17650ms |
| Composite Indices | ||
| Value Score | 47.4 | 100.0 |
| Reasoning Score | 28.2 | 17.0 |
| Intelligence | 28.2 | 17.0 |
| Coding | 52.7 | — |
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.
Solar Pro 4 has the strongest reasoning profile with a 28.2 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
