Model Comparison
GPT-5.1 (high)
vs. GPT-5.5 (high)
Comparing 2 AI models · 10 benchmarks · OpenAI
Recommended Pick
Op GPT-5.1 (high) 10 metric wins Strongest on: Value, Input price, Output price
Best Value
GPT-5.1 (high)
100.0 value score
69.9 reasoning / $3.44/1M
Lowest Price
GPT-5.1 (high)
$1.25/1M input price
Best Reasoning
GPT-5.1 (high)
69.9 reasoning score
Blends available reasoning benchmarks
Best for Coding
GPT-5.5 (high)
58.5 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
GPT-5.1 (high) has the strongest quality-to-price mix at 100.0 out of 100 value points.
Price gap
GPT-5.1 (high) is 4.0x cheaper on input tokens than GPT-5.5 (high).
Speed gap
GPT-5.1 (high) generates about 2.7x as many tokens per second as GPT-5.5 (high).
Reasoning gap
GPT-5.1 (high) leads GPT-5.5 (high) by 4.9 points on reasoning.
Coding gap
GPT-5.5 (high) leads GPT-5.1 (high) by 13.8 points on coding.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
GPT-5.1 (high)
OpenAI
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 (high)
OpenAI
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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Which answer was more useful?
Full Comparison
| Metric | Top Pick Op GPT-5.1 (high) | Op GPT-5.5 (high) |
|---|---|---|
| Pricing per 1M tokens | ||
| Input Cost | $1.25/1M | $5.00/1M |
| Output Cost | $10.00/1M | $30.00/1M |
| Blended (3:1) | $3.44/1M | $11.25/1M |
| Specifications | ||
| Organization | OpenAI | OpenAI |
| Release Date | Nov 13, 2025 | Apr 23, 2026 |
| Performance & Speed | ||
| Throughput | 141.0 tok/s | 52.2 tok/s |
| TTFT | 22221ms | 24868ms |
| Latency | 22221ms | 24868ms |
| Composite Indices | ||
| Value Score | 100.0 | 28.4 |
| Reasoning Score | 69.9 | 65.0 |
| Intelligence | 47.7 | 58.9 |
| Coding | 44.7 | 58.5 |
| Math | 94.0 | — |
| Standard Benchmarks | ||
| GPQA | 87.3% | 93.2% |
| MMLU Pro | 87.0% | — |
| HLE | 26.5% | 43.0% |
| LiveCodeBench | 86.8% | — |
| AIME 2025 | 94.0% | — |
| SciCode | 43.3% | 55.9% |
| LCR | 75.0% | 73.3% |
| IFBench | 72.9% | 71.6% |
| TAU-bench v2 | 81.9% | 93.0% |
| TerminalBench Hard | 45.5% | 59.8% |
Key Takeaways
GPT-5.1 (high) offers the best value at $1.25/1M, making it ideal for high-volume applications and cost-conscious projects.
GPT-5.1 (high) has the strongest reasoning profile with a 69.9 reasoning score, combining the available reasoning-heavy benchmarks.
GPT-5.5 (high) reaches a 58.5 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
GPT-5.1 (high)
- Cost-sensitive applications
- High-volume processing
- Complex reasoning tasks
- Research & analysis
GPT-5.5 (high)
- Code generation
- Software development
