Model Comparison
Step 3.5 Flash
vs. Gemini 3.1 Pro Preview
Comparing 2 AI models · 7 benchmarks · StepFun, Google
Recommended Pick
Go Gemini 3.1 Pro Preview 10 metric wins Strongest on: Reasoning, Intelligence, Coding
Best Value
Step 3.5 Flash
100.0 value score
46.7 reasoning / $0.15/1M
Lowest Price
Step 3.5 Flash
$0.10/1M input price
Best Reasoning
Gemini 3.1 Pro Preview
65.3 reasoning score
Blends available reasoning benchmarks
Best for Coding
Gemini 3.1 Pro Preview
55.5 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 has the strongest quality-to-price mix at 100.0 out of 100 value points.
Price gap
Step 3.5 Flash is 20x cheaper on input tokens than Gemini 3.1 Pro Preview.
Speed gap
Step 3.5 Flash generates about 1.8x as many tokens per second as Gemini 3.1 Pro Preview.
Reasoning gap
Gemini 3.1 Pro Preview leads Step 3.5 Flash by 18.7 points on reasoning.
Coding gap
Gemini 3.1 Pro Preview leads Step 3.5 Flash by 23.9 points on coding.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
Step 3.5 Flash
StepFun
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
Gemini 3.1 Pro Preview
TTFT
—
Time
—
tok/s
—
Tokens
—
Cost
—
Which answer was more useful?
Full Comparison
| Metric | St Step 3.5 Flash | Top Pick Go Gemini 3.1 Pro Preview |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $0.10/1M | $2.00/1M |
| Output Cost | $0.30/1M | $12.00/1M |
| Blended (3:1) | $0.15/1M | $4.50/1M |
| Specifications | ||
| Organization | StepFun | |
| Release Date | Feb 2, 2026 | Feb 19, 2026 |
| Performance & Speed | ||
| Throughput | 219.8 tok/s | 120.2 tok/s |
| TTFT | 850ms | 22543ms |
| Latency | 9950ms | 22543ms |
| Composite Indices | ||
| Value Score | 100.0 | 4.7 |
| Reasoning Score | 46.7 | 65.3 |
| Intelligence | 37.8 | 57.2 |
| Coding | 31.6 | 55.5 |
| Standard Benchmarks | ||
| GPQA | 83.1% | 94.1% |
| HLE | 19.1% | 44.7% |
| SciCode | 40.4% | 58.9% |
| LCR | 43.0% | 72.7% |
| IFBench | 64.6% | 77.1% |
| TAU-bench v2 | 94.4% | 95.6% |
| TerminalBench Hard | 27.3% | 53.8% |
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.
Gemini 3.1 Pro Preview has the strongest reasoning profile with a 65.3 reasoning score, combining the available reasoning-heavy benchmarks.
Gemini 3.1 Pro Preview reaches a 55.5 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
- Cost-sensitive applications
- High-volume processing
Gemini 3.1 Pro Preview
- Complex reasoning tasks
- Research & analysis
- Code generation
- Software development
