Gemini 3.1 Pro Preview vs GPT-5.5
Compare Gemini 3.1 Pro Preview and GPT-5.5 on the metrics that decide an agent workload.
| Metric | Gemini 3.1 Pro Preview | GPT-5.5 |
|---|---|---|
| Provider | Google Gemini | OpenAI |
| Input / 1M | $2.00 | $5.00 |
| Output / 1M | $12.00 | $30.00 |
| Cache read / 1M | $0.20 (−90%) | $0.50 (−90%) |
| Reuse-adj @55% | $3.76 | $9.39 |
| Context | 1M | 1.1M |
| Cache capture | 82% | 88% |
| Warm TTFT | 360ms (−56%) | 240ms (−67%) |
| Quality index | 94 | 96 |
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 is cheaper once prefix reuse is priced in.
Pick GPT-5.5 when it scores higher on the composite quality index, it carries the larger 1.1M context window, it answers faster on warm cache hits.
GPT-5.5 leads on quality while Gemini 3.1 Pro Preview leads on reuse-adjusted cost. Send latency- and budget-sensitive volume to Gemini 3.1 Pro Preview and reserve GPT-5.5 for the hard requests. Zumik's aliases route between them automatically under policy.
Gemini 3.1 Pro Preview vs GPT-5.5, answered.
Is Gemini 3.1 Pro Preview or GPT-5.5 cheaper?
At 55% prefix reuse, Gemini 3.1 Pro Preview blends to about $3.76 per 1M tokens and GPT-5.5 to about $9.39. Gemini 3.1 Pro Preview is cheaper on that basis.
Which has the larger context window?
GPT-5.5 has the larger window: 1.1M vs 1M tokens.
Which captures more reuse?
GPT-5.5 shows higher measured cache capture (88% vs 82%) in the Zumik corpus.
Let an alias pick for you.
Route to whichever model wins under current policy automatically. Zumik resolves the alias to the best fit per request, so you never hard-code a loser.