Model Comparison
GPT-4.5 (Preview)
vs. GPT-5.5 Instant (May 2026)
Comparing 2 AI models · 7 benchmarks · OpenAI
Recommended Pick
Op GPT-5.5 Instant (May 2026) 2 metric wins Strongest on: Reasoning, Intelligence
Lowest Price
GPT-4.5 (Preview)
$0.00/1M input price
Best Reasoning
GPT-5.5 Instant (May 2026)
48.9 reasoning score
Blends available reasoning benchmarks
Best for Coding
GPT-5.5 Instant (May 2026)
45.1 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
GPT-4.5 (Preview) is ∞x cheaper on input tokens than GPT-5.5 Instant (May 2026).
Reasoning gap
GPT-5.5 Instant (May 2026) leads GPT-4.5 (Preview) by 28.9 points on reasoning.
Top-pick rationale
GPT-5.5 Instant (May 2026) wins 2 measurable categories, including Reasoning, Intelligence.
Response Face-Off
Run one prompt through the selected models and compare response quality with live speed and cost context.
GPT-4.5 (Preview)
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 Instant (May 2026)
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 | Op GPT-4.5 (Preview) | Top Pick Op GPT-5.5 Instant (May 2026) |
|---|---|---|
| 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 | OpenAI |
| Release Date | Feb 27, 2025 | May 5, 2026 |
| Performance & Speed | ||
| Throughput | — | — |
| TTFT | — | — |
| Latency | — | — |
| Composite Indices | ||
| Value Score | — | 100.0 |
| Reasoning Score | 20.0 | 48.9 |
| Intelligence | 20.0 | 41.8 |
| Coding | — | 45.1 |
| Standard Benchmarks | ||
| GPQA | — | 84.6% |
| HLE | — | 20.3% |
| SciCode | — | 50.3% |
| LCR | — | 55.7% |
| IFBench | — | 71.5% |
| TAU-bench v2 | — | 49.4% |
| TerminalBench Hard | — | 42.4% |
Key Takeaways
GPT-4.5 (Preview) offers the best value at $0.00/1M, making it ideal for high-volume applications and cost-conscious projects.
GPT-5.5 Instant (May 2026) has the strongest reasoning profile with a 48.9 reasoning score, combining the available reasoning-heavy benchmarks.
GPT-5.5 Instant (May 2026) reaches a 45.1 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
GPT-4.5 (Preview)
- Cost-sensitive applications
- High-volume processing
GPT-5.5 Instant (May 2026)
- Complex reasoning tasks
- Research & analysis
- Code generation
- Software development
