Gemini 3.1 Pro vs GPT-5.6 Terra
Google against OpenAI, costed on the same three workloads. Neither is cheaper everywhere — which one wins depends on how much you read versus write.
Run this comparison on your own numbers
Monthly bill, side by side
| Workload | Gemini 3.1 Pro | GPT-5.6 Terra | Difference |
|---|---|---|---|
| Support chatbot 2,500 six-turn conversations a day |
$8,865 | $8,865 | the same |
| Document summarizer 1,000 single-shot summaries a day |
$1,020 | $1,020 | the same |
| Coding agent 200 twelve-turn sessions a day |
$5,976 | $5,976 | the same |
No prompt caching and no batch discount on either side, so the comparison is like for like. Both figures assume 30 days a month.
The rate cards
| Gemini 3.1 Pro | GPT-5.6 Terra | |
|---|---|---|
| Input, per 1M tokens | $2 | $2 |
| Output, per 1M tokens | $12 | $12 |
| Cached input | $0.2 | $0.2 |
| Context window | 1.05M | 922K |
| Maximum output | 66K | 128K |
| Reasoning model | yes | yes |
| Vision | yes | yes |
Beyond the price
- Gemini 3.1 Pro reads up to 1.05M tokens of context in one request; GPT-5.6 Terra stops at 922K.
- GPT-5.6 Terra can write up to 128K tokens in one response, against 66K for Gemini 3.1 Pro.
- Only GPT-5.6 Terra offers a batch discount — 50% off both rates for work that can wait.
Run this comparison on your own numbers
Full detail: Gemini 3.1 Pro pricing · GPT-5.6 Terra pricing
More comparisons
Other head-to-heads that include Gemini 3.1 Pro or GPT-5.6 Terra.
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- GPT-5.6 Terra vs Claude Opus 4.6
- GPT-5.6 Terra vs Claude Opus 4.7
- GPT-5.6 Terra vs Claude Opus 4.8
Common questions
Which is cheaper, Gemini 3.1 Pro or GPT-5.6 Terra?
Neither is cheaper everywhere — which one wins depends on how much you read versus write.
How much would Gemini 3.1 Pro and GPT-5.6 Terra cost each month?
On PromptSpend's standard workloads, per month: support chatbot: Gemini 3.1 Pro $8,865, GPT-5.6 Terra $8,865 (the same on both); document summarizer: Gemini 3.1 Pro $1,020, GPT-5.6 Terra $1,020 (the same on both); coding agent: Gemini 3.1 Pro $5,976, GPT-5.6 Terra $5,976 (the same on both). No prompt caching and no batch discount is assumed.
How do Gemini 3.1 Pro and GPT-5.6 Terra differ apart from price?
Gemini 3.1 Pro reads up to 1.05M tokens of context in one request; GPT-5.6 Terra stops at 922K. GPT-5.6 Terra can write up to 128K tokens in one response, against 66K for Gemini 3.1 Pro. Only GPT-5.6 Terra offers a batch discount — 50% off both rates for work that can wait.