Claude Opus 4.6 vs Gemini 3.5 Flash vs Gemini 3.1 Pro Preview
Too close to call on our weighted score (Gemini 3.5 Flash 69, Gemini 3.1 Pro Preview 68, Claude Opus 4.6 61). The right pick depends on what you value most.
AnthropicClaude Opus 4.6
61/100- ECI155.3
- Price$5.00 / $25.00
- Context1M
GoogleGemini 3.5 Flash
69/100- ECI154.5
- Price$1.50 / $9.00
- Context1.05M
- Google
Gemini 3.1 Pro Preview
68/100- ECI154.8
- Price$2.00 / $12.00
- Context1.05M
Too close to call
It is close. Our weighted score puts them within 1 points (Gemini 3.5 Flash 69/100, Gemini 3.1 Pro Preview 68/100, Claude Opus 4.6 61/100), so choose by what matters most for your work: Claude Opus 4.6 for raw capability and Gemini 3.5 Flash on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityClaude Opus 4.6Capabilities Index (ECI): Claude Opus 4.6 155.3 · Gemini 3.1 Pro Preview 154.8 · Gemini 3.5 Flash 154.5
- Lowest priceGemini 3.5 FlashGemini 3.5 Flash $3.38 · Gemini 3.1 Pro Preview $4.50 · Claude Opus 4.6 $10.00 per 1M tokens (3:1 blend)
- Longest contextGemini 3.5 Flash and Gemini 3.1 Pro PreviewGemini 3.5 Flash 1,048,576 · Gemini 3.1 Pro Preview 1,048,576 · Claude Opus 4.6 1,000,000 tokens
- Widest inputsGemini 3.5 Flash and Gemini 3.1 Pro PreviewClaude Opus 4.6: Text, Images, PDFs · Gemini 3.5 Flash: Text, Images, PDFs, Audio, Video · Gemini 3.1 Pro Preview: Text, Images, PDFs, Audio, Video
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Claude Opus 4.6 | Gemini 3.5 Flash | Gemini 3.1 Pro Preview |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 85 | 84 | 84 |
| Price | 25% | 2 | 25 | 19 |
| Inputs & features | 15% | 80 | 100 | 100 |
| Context window | 10% | 60 | 61 | 61 |
| Overall | 100% | 61/100 | 69/100 | 68/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Opus 4.6Anthropic | Gemini 3.5 FlashGoogle | Gemini 3.1 Pro PreviewGoogle |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 155.3 (best) | 154.5 | 154.8 |
| ECI rank | #27 of 148 (best) | #33 of 148 | #31 of 148 |
| GPQA DiamondGraduate-level science questions | 90.5% | 92.8% | 94.4% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 66.0% (best) | 62.8% | 59.7% |
| OTIS Mock AIME 2024–2025Competition mathematics | 94.4% | 95.6% | 95.6% (best) |
| SWE-bench VerifiedFixing real GitHub issues | 78.7% | 79.3% (best) | 75.6% |
| SimpleQA VerifiedShort factual questions | 47.0% | 66.2% | 73.5% (best) |
| Price per million tokens | |||
| Input | $5.00 | $1.50 (best) | $2.00 |
| Output | $25.00 | $9.00 (best) | $12.00 |
| Cached input | $0.50 | $0.15 (best) | $0.20 |
| Blended (3:1) | $10.00 | $3.38 (best) | $4.50 |
| Long-context rate | Same rate | Same rate | Over 200K: $4.00 / $18.00 |
| Price source | Official Anthropic API | Official Google API | Official Google API |
| Limits | |||
| Context window | 1,000,000 tokens | 1,048,576 tokens (best) | 1,048,576 tokens (best) |
| Max output | 128,000 tokens (best) | 65,536 tokens | 65,536 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | Yes |
| Audio | No | Yes | Yes |
| Video | No | Yes | Yes |
| Reasoning | Yeslow · medium · high · max | Yesminimal · low · medium · high | Yeslow · medium · high |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | claude-opus-4-6 | gemini-3.5-flash | gemini-3.1-pro-preview |
| API providers | 33 (best) | 32 | 26 |
| Released | Feb 5, 2026 | May 19, 2026 | Feb 19, 2026 |
| Knowledge cutoff | May 31, 2025 | Jan 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.
- Claude Opus 4.6$100.00
- Gemini 3.5 Flash$33.00
- Gemini 3.1 Pro Preview$44.00
Which should you choose?
Which is better: Claude Opus 4.6, Gemini 3.5 Flash or Gemini 3.1 Pro Preview?
It is close. Our weighted score puts them within 1 points (Gemini 3.5 Flash 69/100, Gemini 3.1 Pro Preview 68/100, Claude Opus 4.6 61/100), so choose by what matters most for your work: Claude Opus 4.6 for raw capability and Gemini 3.5 Flash on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Claude Opus 4.6, Gemini 3.5 Flash or Gemini 3.1 Pro Preview?
Gemini 3.5 Flash is cheaper at $1.50 input / $9.00 output per million tokens (official Google API price). Gemini 3.1 Pro Preview costs $2.00 input / $12.00 output per million tokens (official Google API price); Claude Opus 4.6 costs $5.00 input / $25.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $3.38 per million tokens for Gemini 3.5 Flash versus $4.50 for Gemini 3.1 Pro Preview (1.3× as much) and $10.00 for Claude Opus 4.6 (3× as much).
Which scores higher on benchmarks?
Claude Opus 4.6 scores higher on the Capabilities Index (ECI): Claude Opus 4.6 155.3 (#27 of 148), Gemini 3.1 Pro Preview 154.8 (#31 of 148) and Gemini 3.5 Flash 154.5 (#33 of 148). The confidence ranges of the top two overlap (153.4–157.3 vs 152.6–157.3), so treat the gap as small. On individual benchmarks: GPQA Diamond — Gemini 3.1 Pro Preview 94.4%, Gemini 3.5 Flash 92.8%, Claude Opus 4.6 90.5%; FrontierMath Tiers 1–3 — Claude Opus 4.6 66.0%, Gemini 3.5 Flash 62.8%, Gemini 3.1 Pro Preview 59.7%; OTIS Mock AIME 2024–2025 — Gemini 3.1 Pro Preview 95.6%, Gemini 3.5 Flash 95.6%, Claude Opus 4.6 94.4%; SWE-bench Verified — Gemini 3.5 Flash 79.3%, Claude Opus 4.6 78.7%, Gemini 3.1 Pro Preview 75.6%; SimpleQA Verified — Gemini 3.1 Pro Preview 73.5%, Gemini 3.5 Flash 66.2%, Claude Opus 4.6 47.0%.
Which is better for coding?
Gemini 3.5 Flash resolves more real GitHub issues on SWE-bench Verified: Gemini 3.5 Flash 79.3%, Claude Opus 4.6 78.7% and Gemini 3.1 Pro Preview 75.6%. All three support tool calling for agent workflows.
Which has the bigger context window?
Gemini 3.5 Flash and Gemini 3.1 Pro Preview have the largest context windows (1,048,576 and 1,048,576 tokens), against 1,000,000 for Claude Opus 4.6. Maximum output per response: Claude Opus 4.6 up to 128,000, Gemini 3.5 Flash up to 65,536, Gemini 3.1 Pro Preview up to 65,536 tokens.
Which can read images, PDFs, audio or video?
Claude Opus 4.6 accepts text, images and PDFs; Gemini 3.5 Flash accepts text, images, PDFs, audio and video; Gemini 3.1 Pro Preview accepts text, images, PDFs, audio and video. Gemini 3.5 Flash handles the widest range of inputs.
Are any of these open source?
No. Claude Opus 4.6, Gemini 3.5 Flash and Gemini 3.1 Pro Preview are proprietary and only available through APIs and apps.
Which is newer?
Gemini 3.5 Flash is the newest, released May 19, 2026. Gemini 3.1 Pro Preview came out Feb 19, 2026; Claude Opus 4.6 came out Feb 5, 2026. Knowledge cutoff: Claude Opus 4.6 May 31, 2025, Gemini 3.5 Flash Jan 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.
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