GPT-5.5 vs Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview comes out ahead, 68 to 63 on our weighted score, and it is the cheaper option too.
OpenAIGPT-5.5
63/100- ECI159.2
- Price$5.00 / $30.00
- Context1.05M
- Our pick
GoogleGemini 3.1 Pro Preview
68/100- ECI154.8
- Price$2.00 / $12.00
- Context1.05M
Add a model
Make it a three-way comparison.
Gemini 3.1 Pro Preview is our pick
Gemini 3.1 Pro Preview is the better all-round choice, scoring 68/100 against GPT-5.5 (63). It leads on price and inputs & features. GPT-5.5 wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-5.5Capabilities Index (ECI): GPT-5.5 159.2 · Gemini 3.1 Pro Preview 154.8
- Lowest priceGemini 3.1 Pro PreviewGemini 3.1 Pro Preview $4.50 · GPT-5.5 $11.25 per 1M tokens (3:1 blend)
- Longest contextAbout the sameGPT-5.5 1,050,000 · Gemini 3.1 Pro Preview 1,048,576 tokens
- Widest inputsGemini 3.1 Pro PreviewGPT-5.5: Text, Images, PDFs · Gemini 3.1 Pro Preview: Text, Images, PDFs, Audio, Video
- Self-hostingNo open weightsBoth are available only through APIs
| Measure | Weight | GPT-5.5 | Gemini 3.1 Pro Preview |
|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 90 | 84 |
| Price | 25% | 0 | 19 |
| Inputs & features | 15% | 80 | 100 |
| Context window | 10% | 61 | 61 |
| Overall | 100% | 63/100 | 68/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.5OpenAI | Gemini 3.1 Pro PreviewGoogle |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | 159.2 (best) | 154.8 |
| ECI rank | #10 of 148 (best) | #31 of 148 |
| GPQA DiamondGraduate-level science questions | 94.0% | 94.4% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 85.3% (best) | 59.7% |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% (best) | 95.6% |
| SWE-bench VerifiedFixing real GitHub issues | 80.6% (best) | 75.6% |
| SimpleQA VerifiedShort factual questions | 63.0% | 73.5% (best) |
| Price per million tokens | ||
| Input | $5.00 | $2.00 (best) |
| Output | $30.00 | $12.00 (best) |
| Cached input | $0.50 | $0.20 (best) |
| Blended (3:1) | $11.25 | $4.50 (best) |
| Long-context rate | Over 272K: $10.00 / $45.00 | Over 200K: $4.00 / $18.00 |
| Price source | Official OpenAI API | Official Google API |
| Limits | ||
| Context window | 1,050,000 tokens (best) | 1,048,576 tokens |
| Max output | 128,000 tokens (best) | 65,536 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | Yes |
| PDFs | Yes | Yes |
| Audio | No | Yes |
| Video | No | Yes |
| Reasoning | Yeslow · medium · high · xhigh | Yeslow · medium · high |
| Tool calling | Yes | Yes |
| Structured output | Yes | Yes |
| Availability | ||
| Weights | Proprietary | Proprietary |
| API model ID | gpt-5.5 | gemini-3.1-pro-preview |
| API providers | 42 (best) | 26 |
| Released | Apr 23, 2026 | Feb 19, 2026 |
| Knowledge cutoff | Dec 1, 2025 | Jan 2025 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-5.5$110.00
- Gemini 3.1 Pro Preview$44.00
Which should you choose?
Which is better: GPT-5.5 or Gemini 3.1 Pro Preview?
Gemini 3.1 Pro Preview is the better all-round choice, scoring 68/100 against GPT-5.5 (63). It leads on price and inputs & features. GPT-5.5 wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-5.5 or Gemini 3.1 Pro Preview?
Gemini 3.1 Pro Preview is cheaper at $2.00 input / $12.00 output per million tokens (official Google API price). GPT-5.5 costs $5.00 input / $30.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $4.50 per million tokens for Gemini 3.1 Pro Preview versus $11.25 for GPT-5.5 (2.5× as much).
Which scores higher on benchmarks?
GPT-5.5 scores higher on the Capabilities Index (ECI): GPT-5.5 159.2 (#10 of 148) and Gemini 3.1 Pro Preview 154.8 (#31 of 148). The confidence ranges of the top two overlap (156.9–162.4 vs 152.6–157.3), so treat the gap as small. On individual benchmarks: GPQA Diamond — Gemini 3.1 Pro Preview 94.4%, GPT-5.5 94.0%; FrontierMath Tiers 1–3 — GPT-5.5 85.3%, Gemini 3.1 Pro Preview 59.7%; OTIS Mock AIME 2024–2025 — GPT-5.5 100%, Gemini 3.1 Pro Preview 95.6%; SWE-bench Verified — GPT-5.5 80.6%, Gemini 3.1 Pro Preview 75.6%; SimpleQA Verified — Gemini 3.1 Pro Preview 73.5%, GPT-5.5 63.0%.
Which is better for coding?
GPT-5.5 resolves more real GitHub issues on SWE-bench Verified: GPT-5.5 80.6% and Gemini 3.1 Pro Preview 75.6%. Both support tool calling for agent workflows.
Which has the bigger context window?
Their context windows are effectively the same size: GPT-5.5 1,050,000 and Gemini 3.1 Pro Preview 1,048,576 tokens. Maximum output per response: GPT-5.5 up to 128,000, Gemini 3.1 Pro Preview up to 65,536 tokens.
Which can read images, PDFs, audio or video?
GPT-5.5 accepts text, images and PDFs; Gemini 3.1 Pro Preview accepts text, images, PDFs, audio and video. Gemini 3.1 Pro Preview handles the widest range of inputs.
Are any of these open source?
No. GPT-5.5 and Gemini 3.1 Pro Preview are proprietary and only available through APIs and apps.
Which is newer?
GPT-5.5 is the newest, released Apr 23, 2026. Gemini 3.1 Pro Preview came out Feb 19, 2026. Knowledge cutoff: GPT-5.5 Dec 1, 2025, Gemini 3.1 Pro Preview Jan 2025.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
Related comparisons
- Add Claude Opus 4.8Three-way comparison
- GPT-5.5 vs Claude Opus 4.8Anthropic · ECI 158.3
- GPT-5.5 vs Kimi K3Moonshot AI · ECI 157.6
- GPT-5.5 vs Qwen3.8 MaxAlibaba (Qwen) · ECI 156.6
- Gemini 3.1 Pro Preview vs GPT-5.3 CodexOpenAI · ECI 156.8
- Gemini 3.1 Pro Preview vs Qwen3.7 MaxAlibaba (Qwen) · ECI 153.7
- Gemini 3.1 Pro Preview vs Claude Sonnet 4.6Anthropic · ECI 152.3
