Head-to-head
Gemini 3.1 Pro Preview vs GPT-5.5 Pro
Compare Gemini 3.1 Pro Preview and GPT-5.5 Pro on the metrics that decide an agent workload.
| Metric | Gemini 3.1 Pro Preview | GPT-5.5 Pro |
|---|---|---|
| Provider | Google Gemini | OpenAI |
| Input / 1M | $2.00 | $30.00 |
| Output / 1M | $12.00 | $180.00 |
| Cache read / 1M | $0.20 (−90%) | $30.00 (−0%) |
| Reuse-adj @55% | $3.76 | $67.50 |
| Context | 1M | 1.1M |
| Cache capture | 83% | 80% |
| Warm TTFT | 360ms (−56%) | 900ms (−53%) |
| Quality index | 94 | 86 |
Teal marks the better value in each row. Reuse-adjusted assumes 55% prefix reuse and a 25% output share.
Pick Gemini 3.1 Pro Preview when it scores higher on the composite quality index, it is cheaper once prefix reuse is priced in, it answers faster on warm cache hits.
Pick GPT-5.5 Pro when it carries the larger 1.1M context window.
Gemini 3.1 Pro Preview wins on both reuse-adjusted cost and quality here, so it is the default pick. Reach for GPT-5.5 Pro only when a specific constraint (modality, latency floor, or licensing) forces it.
Frequently asked
Gemini 3.1 Pro Preview vs GPT-5.5 Pro, answered.
Is Gemini 3.1 Pro Preview or GPT-5.5 Pro cheaper?
At 55% prefix reuse, Gemini 3.1 Pro Preview blends to about $3.76 per 1M tokens and GPT-5.5 Pro to about $67.50. Gemini 3.1 Pro Preview is cheaper on that basis.
Which has the larger context window?
GPT-5.5 Pro has the larger window: 1.1M vs 1M tokens.
Which captures more reuse?
Gemini 3.1 Pro Preview shows higher measured cache capture (83% vs 80%) in the Zumik corpus.
Let an alias pick for you.
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