Gemini 3.1 Pro Preview vs GPT-5.5 Instant
Gemini 3.1 Pro Preview (2026) and GPT-5.5 Instant (2026) are general-purpose language models from Google DeepMind and OpenAI. Gemini 3.1 Pro Preview ships a 1m-token context window, while GPT-5.5 Instant ships a 400k-token context window. On MMMU Pro, Gemini 3.1 Pro Preview leads by 12.2 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
GPT-5.5 Instant is safer overall; choose Gemini 3.1 Pro Preview when coding workflow support matters.
Decision scorecard
Local evidence first| Signal | Gemini 3.1 Pro Preview | GPT-5.5 Instant |
|---|---|---|
| Best for | multimodal apps, tool-calling agents, and long-context analysis | multimodal apps and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 400k |
| Cheapest output | $12/1M tokens | $30/1M tokens |
| Provider routes | 5 tracked | 1 tracked |
| Shared benchmarks | MMMU Pro leader | 1 shared |
Decision tradeoffs
- Gemini 3.1 Pro Preview holds a shared-benchmark lead on MMMU Pro, ahead by 12.2 points.
- Gemini 3.1 Pro Preview has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.1 Pro Preview has the lower cheapest tracked output price at $12/1M tokens.
- Gemini 3.1 Pro Preview has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags Gemini 3.1 Pro Preview for Coding, RAG, and Agents.
- Local decision data tags GPT-5.5 Instant for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Gemini 3.1 Pro Preview
$4,600
Cheapest tracked route/tier: Google AI Studio
GPT-5.5 Instant
$11,500
Cheapest tracked route/tier: OpenAI API
Estimated monthly gap: $6,900. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Gemini 3.1 Pro Preview and GPT-5.5 Instant; plan for SDK, billing, or endpoint changes.
- GPT-5.5 Instant is $18/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- No overlapping tracked provider route is sourced for GPT-5.5 Instant and Gemini 3.1 Pro Preview; plan for SDK, billing, or endpoint changes.
- Gemini 3.1 Pro Preview is $18/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-02-19 | 2026-05-05 |
| Context window | 1m | 400k |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-01 | 2025-08 |
Pricing and availability
| Pricing attribute | Gemini 3.1 Pro Preview | GPT-5.5 Instant |
|---|---|---|
| Input price |
| $5/1M tokens |
| Output price |
| $30/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 3.1 Pro Preview | GPT-5.5 Instant |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | No |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Gemini 3.1 Pro Preview | GPT-5.5 Instant |
|---|---|---|
| MMMU Pro | 88.2 | 76.0 |
Continue comparing
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.