GPT-5.5 Pro vs Gemini 3.1 Pro Preview
Side-by-side comparison across metrics, pricing, and overall score — every value traced to a source.
Verdict: Gemini 3.1 Pro Preview ranks highest overall (#5) with a score of 50.8.
The best choice still depends on which metrics matter for your workload — per-metric winners are marked below.
What the numbers hide
Computed from the published values below — no estimates, no generated claims.
Fragile verdict
The overall winner flips to GPT-5.5 Pro if Context Window is weighted at 40% (it counts for 18% today). If context window drives your decision, the ranking above may not be your ranking.
Fragile verdict
The overall winner flips to GPT-5.5 Pro if Max Output Tokens is weighted at 30% (it counts for 6% today). If max output tokens drives your decision, the ranking above may not be your ranking.
Real tradeoff
GPT-5.5 Pro clearly beats Gemini 3.1 Pro Preview on Context Window but clearly loses on Input Price — this pair is a priorities question, not a quality question.
What nobody reports
Cache Read Price (1 of 2 missing) · SWE-Bench Pro Score (1 of 2 missing) — the questions worth asking vendors directly.
AI hot take
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| Metric | GPT-5.5 ProOpenAI | Gemini 3.1 Pro PreviewGoogle |
|---|---|---|
| Overall OptiSift Score | 31.9#10 | 50.8#5 |
| Input Price | $30 | $2 |
| Output Price | $180 | $12 |
| Cache Read Price | — | $0.2 |
| Context Window | 1.1M | 1.0M |
| Max Output Tokens | 128K | 66K |
| SWE-Bench Pro Score | — | 54.2% |
| Tool Calling | Yes | Yes |
| Extended Reasoning | Yes | Yes |
About these models
#10GPT-5.5 Pro
OpenAI
GPT-5.5 Pro is OpenAI's reasoning-capable model: $30/$180 per 1M input/output tokens, 1.1M token context window.
#5Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview is Google's reasoning-capable model: $2/$12 per 1M input/output tokens, 1.0M token context window, 54.2% on SWE-Bench Pro.