Gemini 3.1 Pro vs Gemini 3 Pro: Upgrade Now (March 9, 2026 Deadline)
Gemini 3 Pro is deprecated March 9, 2026. The model string gemini-3-pro-preview will stop responding after that date. The replacement is Gemini 3.1 Pro — identical pricing ($2/$12 per 1M tokens), the same 1M token context window, and significantly better reasoning across every benchmark where the two have been compared. This is not an optional upgrade.
Last updated: February 2026
Our Pick
Gemini 3.1 Pro
Switch to Gemini 3.1 Pro. Same price, same context window, materially better reasoning — and Gemini 3 Pro stops working March 9, 2026. ARC-AGI-2 more than doubled (77.1% vs 31.1%). SWE-Bench improved to 80.6% from 76.2%. A documented output truncation bug that silently cut code at ~21K tokens was fixed. The only real trade-off is latency: Gemini 3.1 Pro's time to first token is 29.96s in reasoning mode, which is high for interactive use. If you run real-time interfaces, test the latency impact before switching. For batch workloads and agentic pipelines, switch now.
Try Gemini 3.1 ProAt a glance
| Feature | Gemini 3.1 Pro | Gemini 3 Pro |
|---|---|---|
| Rating | 8.7 / 10 | 7.8 / 10 |
| Provider | ||
| Context window | 1M tokens | 1M tokens |
| Input (per 1M tokens) | $2 | $2 |
| Output (per 1M tokens) | $12 | $12 |
| Multimodal | Yes | Yes |
| Open source | No | No |
Use case breakdown
Gemini 3 Pro is deprecated March 9, 2026. API calls will fail after that date. Gemini 3.1 Pro has no announced deprecation date. This alone makes the migration non-negotiable.
ARC-AGI-2: 77.1% vs 31.1% — more than doubled. For tasks requiring novel logic, multi-step reasoning, or abstract problem-solving, 3.1 Pro is in a different tier.
APEX-Agents: 33.5% vs 18.4% — nearly doubled. MCP Atlas: 69.2% vs 54.1%. BrowseComp: 85.9% vs 59.2%. 3.1 Pro leads across every agentic benchmark by a wide margin.
SWE-Bench Verified: 80.6% vs 76.2%. Output truncation bug (which silently cut code at ~21K tokens) fixed. 3.1 Pro also adds a dedicated custom-tools API endpoint for agentic pipelines.
GPQA Diamond: 94.3% vs 91.9%. Humanity's Last Exam: 44.4% vs 37.5%. 3.1 Pro leads on every scientific reasoning benchmark.
Gemini 3.1 Pro's time to first token is 29.96s in reasoning mode — noticeably high for interactive use. Gemini 3 Pro responds faster. But given the March 9 deprecation, this advantage is temporary. Test your specific latency requirements against 3.1 Pro before committing to anything that depends on 3 Pro's speed.
FAQ
When is Gemini 3 Pro being deprecated?
March 9, 2026. The model string gemini-3-pro-preview will stop responding after that date. The migration path is gemini-3.1-pro-preview — same pricing, no API cost change.
Is Gemini 3.1 Pro better than Gemini 3 Pro?
Yes, significantly. ARC-AGI-2 abstract reasoning more than doubled (77.1% vs 31.1%). SWE-Bench Verified improved from 76.2% to 80.6%. Humanity's Last Exam went from 37.5% to 44.4%. A documented truncation bug that silently cut code output at ~21K tokens was fixed. All at the same price.
Is Gemini 3.1 Pro the same price as Gemini 3 Pro?
Yes. Both are $2/1M input and $12/1M output (≤200K context), $4/$18 over 200K. Google held the price flat for the upgrade.
Will Gemini 3.1 Pro replace Gemini 3 Pro on the free consumer tier?
Not immediately — the free consumer product at gemini.google.com runs Gemini Flash models, not Pro. Gemini 3.1 Pro requires Google AI Pro ($19.99/month) or Google AI Ultra ($249.99/month) for consumer access. The API free tier includes Gemini Flash only.