Google: Gemini 2.5 Flash vs Google: Gemini 3.1 Pro Preview: Which AI Model Is Better?
Updated March 24, 2026· Based on independent benchmark data
Quick Verdict
Google: Gemini 3.1 Pro Preview leads in intelligence with a score of 57.2 vs 19.4. Google: Gemini 2.5 Flash is 6.7x cheaper at $0.30/1M tokens vs $2.00/1M. For speed, Google: Gemini 2.5 Flash wins at 343 tok/s vs 117 tok/s.
Head-to-Head Comparison
| Metric | Google: Gemini 2.5 Flash | Google: Gemini 3.1 Pro Preview |
|---|---|---|
| Intelligence Score | 19.4 | 57.2 |
| Coding Score | 14.5 | 55.5 |
| Math Score | 46.7 | N/A |
| Speed (tok/s) | 343 tok/s | 117 tok/s |
| Latency (TTFT) | 0.31s | 21.91s |
| Input Price / 1M tokens | $0.30 | $2.00 |
| Output Price / 1M tokens | $2.50 | $12 |
| Context Window | 1.0M | 1.0M |
| Max Output Tokens | 66K | 66K |
| Input Modalities | File + Image + Text + Audio + Video | Audio + File + Image + Text + Video |
| Output Modalities | Text | Text |
| Free Tier | No | No |
Detailed Analysis
Intelligence & Quality
Google: Gemini 3.1 Pro Preview outperforms Google: Gemini 2.5 Flash on the Artificial Analysis intelligence index with a score of 57.2 compared to 19.4. For coding tasks, Google: Gemini 3.1 Pro Preview has the edge with a coding score of 55.5 vs 14.5.
Speed & Latency
Google: Gemini 2.5 Flash generates output significantly faster at 343 tok/s compared to Google: Gemini 3.1 Pro Preview's 117 tok/s, making it 2.9x faster for streaming responses. Time to first token is 0.31s for Google: Gemini 2.5 Flash vs 21.91s for Google: Gemini 3.1 Pro Preview, which affects perceived responsiveness in interactive applications.
Pricing
Google: Gemini 2.5 Flash is more affordable at $0.30/1M input tokens ($2.50/1M output), while Google: Gemini 3.1 Pro Preview costs $2.00/1M input ($12/1M output). That makes Google: Gemini 3.1 Pro Preview 6.7x more expensive per token, which can add up significantly at scale. For a typical workload of 100 requests per day at 2,000 tokens each, Google: Gemini 2.5 Flash would cost approximately $1.80/month vs $12.00/month for Google: Gemini 3.1 Pro Preview in input costs alone.
Context Window
Both models support the same context window of 1.0M tokens (approximately 524 pages of text). For output length, Google: Gemini 3.1 Pro Preview can generate up to 66K tokens per response vs 66K for Google: Gemini 2.5 Flash.
Best Use Cases
Choose Google: Gemini 2.5 Flash when you need faster output (343 tok/s), lower cost. Choose Google: Gemini 3.1 Pro Preview when you need higher intelligence (57.2), stronger coding performance (55.5).
Choose Google: Gemini 2.5 Flash if:
- ✓You need faster throughput (343 tok/s vs 117 tok/s)
- ✓You want lower latency (0.31s vs 21.91s TTFT)
- ✓Budget is a concern ($0.30/1M vs $2.00/1M)
Choose Google: Gemini 3.1 Pro Preview if:
- ✓You need higher intelligence (score: 57.2 vs 19.4)
- ✓You prioritize coding performance (score: 55.5 vs 14.5)
Frequently Asked Questions
Is Google: Gemini 2.5 Flash better than Google: Gemini 3.1 Pro Preview for coding?
Google: Gemini 3.1 Pro Preview scores higher on coding benchmarks (55.5 vs 14.5), making it the better choice for programming tasks.
Which is cheaper, Google: Gemini 2.5 Flash or Google: Gemini 3.1 Pro Preview?
Google: Gemini 2.5 Flash is cheaper at $0.30/1M input tokens vs $2.00/1M for Google: Gemini 3.1 Pro Preview.
Is Google: Gemini 2.5 Flash faster than Google: Gemini 3.1 Pro Preview?
Google: Gemini 2.5 Flash is faster, producing output at 343 tok/s compared to Google: Gemini 3.1 Pro Preview's 117 tok/s.
Can Google: Gemini 2.5 Flash process images?
Yes, Google: Gemini 2.5 Flash supports image input. Google: Gemini 3.1 Pro Preview also supports images.
Which has a larger context window, Google: Gemini 2.5 Flash or Google: Gemini 3.1 Pro Preview?
Both models have the same context window of 1.0M tokens.
Should I use Google: Gemini 2.5 Flash or Google: Gemini 3.1 Pro Preview?
It depends on your priorities. Google: Gemini 3.1 Pro Preview scores higher on intelligence (57.2), but Google: Gemini 2.5 Flash may be better for specific use cases like budget-conscious projects or speed-critical applications.
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Benchmark data by Artificial Analysis
Data last synced: March 24, 2026