Model comparison
GPT-5.5 Pro vs Gemini 3.1 Pro Preview
Compare GPT-5.5 Pro vs Gemini 3.1 Pro Preview API pricing: input/output token costs, cache pricing, context windows, workload estimates, and routing fit.
GPT-5.5 Pro
openai · gpt-5.5-pro
- Input
- $30
- Output
- $180
- Context
- 1.1M
Gemini 3.1 Pro Preview
gemini · gemini/gemini-3.1-pro-preview
- Input
- $2
- Output
- $12
- Context
- 1M
Quick take
Gemini 3.1 Pro Preview has the lower input price at $2 per 1M input tokens. Gemini 3.1 Pro Preview is cheaper for the example blended workload below. GPT-5.5 Pro has the larger context window at 1.1M tokens.
Choose GPT-5.5 Pro if...
- GPT-5.5 Pro is safer for long documents, repository analysis, and RAG prompts because it has the larger context window.
- GPT-5.5 Pro gives more room for long generated answers, reports, or code output.
Choose Gemini 3.1 Pro Preview if...
- Gemini 3.1 Pro Preview is the better default for cost-sensitive traffic and repeated high-volume calls.
Example workload cost
Estimates use input tokens plus 20% output tokens. They exclude provider discounts, cache hits, and tool/search surcharges.
| Workload | GPT-5.5 Pro | Gemini 3.1 Pro Preview | Cheaper |
|---|---|---|---|
| 1M input + 200K output | $66.00 | $4.40 | Gemini 3.1 Pro Preview |
| 10M input + 2M output | $660.00 | $44.00 | Gemini 3.1 Pro Preview |
| 100M input + 20M output | $6,600.00 | $440.00 | Gemini 3.1 Pro Preview |
Context, output, and capability fit
GPT-5.5 Pro provides the larger context window. Check max output separately when the task needs long reports, code generation, or full-document rewrites.
- GPT-5.5 Pro max output
- 128K
- Gemini 3.1 Pro Preview max output
- 65.5K
- GPT-5.5 Pro features
- prompt caching, function calling, vision
- Gemini 3.1 Pro Preview features
- prompt caching, function calling, vision
Risk notes for GPT-5.5 Pro
- High output price: cap max tokens for verbose generation workloads.
Risk notes for Gemini 3.1 Pro Preview
- Preview or beta model: verify availability and pricing before production rollout.
Routing tags
frontierpremiumreasoningcodingagentslong-contextmultimodalcache-friendlyragpreviewenterprise-rag