Model Comparison
Gemini 1.5 Flash (Sep '24)
vs. GPT-5.5 (xhigh)
Comparing 2 AI models · 11 benchmarks · Google, OpenAI
Recommended Pick
Op GPT-5.5 (xhigh) 6 metric wins Strongest on: Throughput, Reasoning, Intelligence
Lowest Price
Gemini 1.5 Flash (Sep '24)
$0.00/1M input price
Best Reasoning
GPT-5.5 (xhigh)
66.0 reasoning score
Blends available reasoning benchmarks
Best for Coding
GPT-5.5 (xhigh)
59.1 coding index
Composite Indices
Higher is better; speed and price are normalized
Standard Benchmarks
Only benchmarks with data are shown
Differences That Matter
Price gap
Gemini 1.5 Flash (Sep '24) is ∞x cheaper on input tokens than GPT-5.5 (xhigh).
Reasoning gap
GPT-5.5 (xhigh) leads Gemini 1.5 Flash (Sep '24) by 33.1 points on reasoning.
Top-pick rationale
GPT-5.5 (xhigh) wins 6 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.
Gemini 1.5 Flash (Sep '24)
TTFT
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Time
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tok/s
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Tokens
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Cost
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GPT-5.5 (xhigh)
OpenAI
TTFT
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Time
—
tok/s
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Tokens
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Cost
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Which answer was more useful?
Full Comparison
| Metric | Go Gemini 1.5 Flash (Sep '24) | Top Pick Op GPT-5.5 (xhigh) |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $0.00/1M | $5.00/1M |
| Output Cost | $0.00/1M | $30.00/1M |
| Blended (3:1) | — | $11.25/1M |
| Specifications | ||
| Organization | OpenAI | |
| Release Date | Sep 24, 2024 | Apr 23, 2026 |
| Performance & Speed | ||
| Throughput | — | 66.5 tok/s |
| TTFT | — | 37889ms |
| Latency | — | 37889ms |
| Composite Indices | ||
| Value Score | — | 100.0 |
| Reasoning Score | 32.9 | 66.0 |
| Intelligence | 13.8 | 60.2 |
| Coding | — | 59.1 |
| Standard Benchmarks | ||
| GPQA | 46.3% | 93.5% |
| MMLU Pro | 68.0% | — |
| HLE | 3.5% | 44.3% |
| LiveCodeBench | 27.3% | — |
| MATH 500 | 82.7% | — |
| AIME (Original) | 18.0% | — |
| SciCode | 26.7% | 56.1% |
| LCR | — | 74.3% |
| IFBench | — | 75.9% |
| TAU-bench v2 | — | 93.9% |
| TerminalBench Hard | — | 60.6% |
Key Takeaways
Gemini 1.5 Flash (Sep '24) offers the best value at $0.00/1M, making it ideal for high-volume applications and cost-conscious projects.
GPT-5.5 (xhigh) has the strongest reasoning profile with a 66.0 reasoning score, combining the available reasoning-heavy benchmarks.
GPT-5.5 (xhigh) reaches a 59.1 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
Gemini 1.5 Flash (Sep '24)
- Cost-sensitive applications
- High-volume processing
GPT-5.5 (xhigh)
- Complex reasoning tasks
- Research & analysis
- Code generation
- Software development
