Model Comparison
Sonar Reasoning
vs. Step 3.5 Flash 2603
Comparing 2 AI models · 9 benchmarks · Perplexity, StepFun
Recommended Pick
PeSonar Reasoning5 metric winsStrongest on: Input price, Output price, TTFT
Lowest Price
Sonar Reasoning
$0.00/1M input price
Best Reasoning
Sonar Reasoning
60.8 reasoning score
Blends available reasoning benchmarks
Composite Indices
Higher is better; speed and price are normalized
Standard Benchmarks
Only benchmarks with data are shown
Differences That Matter
Price gap
Sonar Reasoning is ∞x cheaper on input tokens than Step 3.5 Flash 2603.
Reasoning gap
Sonar Reasoning leads Step 3.5 Flash 2603 by 17.0 points on reasoning.
Top-pick rationale
Sonar Reasoning wins 5 measurable categories, including Input price, Output price, TTFT, Latency.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
Sonar Reasoning
Perplexity
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 Pe Sonar Reasoning | St Step 3.5 Flash 2603 |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $0.00/1M | $0.10/1M |
| Output Cost | $0.00/1M | $0.30/1M |
| Blended (3:1) | — | $0.15/1M |
| Specifications | ||
| Organization | Perplexity | StepFun |
| Release Date | Jan 28, 2025 | Apr 2, 2026 |
| Performance & Speed | ||
| Throughput | — | 212.5 tok/s |
| TTFT | — | 751ms |
| Latency | — | 10162ms |
| Composite Indices | ||
| Value Score | — | 100.0 |
| Reasoning Score | 60.8 | 43.7 |
| Intelligence | 11.7 | 26.0 |
| Standard Benchmarks | ||
| GPQA | 62.3% | 82.6% |
| HLE | — | 22.6% |
| MATH 500 | 92.1% | — |
| AIME (Original) | 77.0% | — |
| SciCode | — | 38.5% |
| LCR | — | 54.3% |
| IFBench | — | 66.5% |
| TAU-bench v2 | — | 87.4% |
| TerminalBench Hard | — | 32.6% |
Key Takeaways
Sonar Reasoning offers the best value at $0.00/1M,making it ideal for high-volume applications and cost-conscious projects.
Sonar Reasoning has the strongest reasoning profile with a 60.8 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
Sonar Reasoning
- Cost-sensitive applications
- High-volume processing
- Complex reasoning tasks
- Research & analysis
Step 3.5 Flash 2603
- General-purpose AI
- Versatile applications
