Gemini 3.1 Pro vs GPT-5.5: API Pricing
Input and output token rates, context windows, and real monthly cost for Gemini 3.1 Pro (Google) and GPT-5.5 (OpenAI), side by side. Prices are standard on-demand rates as of June 2026.
The short answer
For a typical coding-agent workload (60M in / 12M out per month), Gemini 3.1 Pro is the cheaper option at $264/mo versus $660/mo for GPT-5.5 - about 60% less (2.5× cheaper). On the headline sticker of 1M input + 1M output, Gemini 3.1 Pro is $14.00 and GPT-5.5 is $35.00.
Rates at a glance
| Gemini 3.1 Pro | GPT-5.5 | |
|---|---|---|
| Input ($/1M tokens) | $2.00 | $5.00 |
| Output ($/1M tokens) | $12.00 | $30.00 |
| Blended (1M in + 1M out) | $14.00 | $35.00 |
| Context window | 1,000K | 1,050K |
| Type | Proprietary | Proprietary |
| Provider | OpenAI |
Monthly cost by workload
Estimated monthly API spend at each workload's token volume. Output usually costs several times input, so the winner can flip with your mix.
| Workload | Gemini 3.1 Pro | GPT-5.5 | Cheaper |
|---|---|---|---|
| Chatbot / assistant 10M in / 3M out | $56.00/mo | $140/mo | Gemini 3.1 Pro |
| Coding agent 60M in / 12M out | $264/mo | $660/mo | Gemini 3.1 Pro |
| RAG / summarization 40M in / 4M out | $128/mo | $320/mo | Gemini 3.1 Pro |
| Batch / classification 20M in / 2M out | $64.00/mo | $160/mo | Gemini 3.1 Pro |
Want your own in/out split? Use the full interactive comparator to rank every model and provider for your exact workload.
Frequently asked questions
Is Gemini 3.1 Pro or GPT-5.5 cheaper?
It depends on your input/output mix, but for a typical coding-agent workload (60M in / 12M out per month) Gemini 3.1 Pro costs $264/mo versus $660/mo for GPT-5.5 - about 60% less (2.5x). On the headline sticker (1M input + 1M output), Gemini 3.1 Pro is $14.00 and GPT-5.5 is $35.00.
What are the token rates for Gemini 3.1 Pro and GPT-5.5?
Gemini 3.1 Pro (Google) is $2.00 per 1M input and $12.00 per 1M output. GPT-5.5 (OpenAI) is $5.00 per 1M input and $30.00 per 1M output. These are standard on-demand rates, not cached or batch.
Is Gemini 3.1 Pro or GPT-5.5 open-weight?
Gemini 3.1 Pro is proprietary and GPT-5.5 is proprietary. Both are closed models billed only through their owner's API.
What context window do Gemini 3.1 Pro and GPT-5.5 support?
Gemini 3.1 Pro supports 1,000K tokens and GPT-5.5 supports 1,050K tokens. Some models also step up pricing past a size threshold - check the source pricing pages for long-context tiers.
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