Claude Opus 4.6 vs GPT-5.3 Codex vs Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview comes out ahead, 68 to 64 and 61 on our weighted score, and it is the cheaper option too.
AnthropicClaude Opus 4.6
61/100- ECI155.3
- Price$5.00 / $25.00
- Context1M
OpenAIGPT-5.3 Codex
64/100- ECI156.8
- Price$1.75 / $14.00
- Context400K
- Our pick
GoogleGemini 3.1 Pro Preview
68/100- ECI154.8
- Price$2.00 / $12.00
- Context1.05M
Gemini 3.1 Pro Preview is our pick
Gemini 3.1 Pro Preview is the better all-round choice, scoring 68/100 against GPT-5.3 Codex (64) and Claude Opus 4.6 (61). It leads on inputs & features. GPT-5.3 Codex wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-5.3 CodexCapabilities Index (ECI): GPT-5.3 Codex 156.8 · Claude Opus 4.6 155.3 · Gemini 3.1 Pro Preview 154.8
- Lowest priceGemini 3.1 Pro PreviewGemini 3.1 Pro Preview $4.50 · GPT-5.3 Codex $4.81 · Claude Opus 4.6 $10.00 per 1M tokens (3:1 blend)
- Longest contextGemini 3.1 Pro PreviewGemini 3.1 Pro Preview 1,048,576 · Claude Opus 4.6 1,000,000 · GPT-5.3 Codex 400,000 tokens
- Widest inputsGemini 3.1 Pro PreviewClaude Opus 4.6: Text, Images, PDFs · GPT-5.3 Codex: Text, Images, PDFs · 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 | GPT-5.3 Codex | Gemini 3.1 Pro Preview |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 85 | 87 | 84 |
| Price | 25% | 2 | 18 | 19 |
| Inputs & features | 15% | 80 | 80 | 100 |
| Context window | 10% | 60 | 44 | 61 |
| Overall | 100% | 61/100 | 64/100 | 68/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Opus 4.6Anthropic | GPT-5.3 CodexOpenAI | Gemini 3.1 Pro PreviewGoogle |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 155.3 | 156.8 (best) | 154.8 |
| ECI rank | #27 of 148 | #18 of 148 (best) | #31 of 148 |
| GPQA DiamondGraduate-level science questions | 90.5% | — | 94.4% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 66.0% (best) | — | 59.7% |
| OTIS Mock AIME 2024–2025Competition mathematics | 94.4% | — | 95.6% (best) |
| SWE-bench VerifiedFixing real GitHub issues | 78.7% (best) | 74.8% | 75.6% |
| SimpleQA VerifiedShort factual questions | 47.0% | — | 73.5% (best) |
| Price per million tokens | |||
| Input | $5.00 | $1.75 (best) | $2.00 |
| Output | $25.00 | $14.00 | $12.00 (best) |
| Cached input | $0.50 | $0.175 (best) | $0.20 |
| Blended (3:1) | $10.00 | $4.81 | $4.50 (best) |
| Long-context rate | Same rate | Same rate | Over 200K: $4.00 / $18.00 |
| Price source | Official Anthropic API | Official OpenAI API | Official Google API |
| Limits | |||
| Context window | 1,000,000 tokens | 400,000 tokens | 1,048,576 tokens (best) |
| Max output | 128,000 tokens (best) | 128,000 tokens (best) | 65,536 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | Yes |
| Audio | No | No | Yes |
| Video | No | No | Yes |
| Reasoning | Yeslow · medium · high · max | Yeslow · medium · high · xhigh | 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 | gpt-5.3-codex | gemini-3.1-pro-preview |
| API providers | 33 (best) | 19 | 26 |
| Released | Feb 5, 2026 | Feb 5, 2026 | Feb 19, 2026 |
| Knowledge cutoff | May 31, 2025 | Aug 31, 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
- GPT-5.3 Codex$45.50
- Gemini 3.1 Pro Preview$44.00
Which should you choose?
Which is better: Claude Opus 4.6, GPT-5.3 Codex or Gemini 3.1 Pro Preview?
Gemini 3.1 Pro Preview is the better all-round choice, scoring 68/100 against GPT-5.3 Codex (64) and Claude Opus 4.6 (61). It leads on inputs & features. GPT-5.3 Codex wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Claude Opus 4.6, GPT-5.3 Codex 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-5.3 Codex costs $1.75 input / $14.00 output per million tokens (official OpenAI 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 $4.50 per million tokens for Gemini 3.1 Pro Preview versus $4.81 for GPT-5.3 Codex (1.1× as much) and $10.00 for Claude Opus 4.6 (2.2× as much).
Which scores higher on benchmarks?
GPT-5.3 Codex scores higher on the Capabilities Index (ECI): GPT-5.3 Codex 156.8 (#18 of 148), Claude Opus 4.6 155.3 (#27 of 148) and Gemini 3.1 Pro Preview 154.8 (#31 of 148). The confidence ranges of the top two overlap (153.5–160.8 vs 153.4–157.3), so treat the gap as small. On individual benchmarks: SWE-bench Verified — Claude Opus 4.6 78.7%, Gemini 3.1 Pro Preview 75.6%, GPT-5.3 Codex 74.8%.
Which is better for coding?
Claude Opus 4.6 resolves more real GitHub issues on SWE-bench Verified: Claude Opus 4.6 78.7%, Gemini 3.1 Pro Preview 75.6% and GPT-5.3 Codex 74.8%. All three support tool calling for agent workflows.
Which has the bigger context window?
Gemini 3.1 Pro Preview has the largest context window at 1,048,576 tokens, against 1,000,000 for Claude Opus 4.6 and 400,000 for GPT-5.3 Codex. Maximum output per response: Claude Opus 4.6 up to 128,000, GPT-5.3 Codex up to 128,000, 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; GPT-5.3 Codex 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. Claude Opus 4.6, GPT-5.3 Codex and Gemini 3.1 Pro Preview are proprietary and only available through APIs and apps.
Which is newer?
Gemini 3.1 Pro Preview is the newest, released Feb 19, 2026. Claude Opus 4.6 came out Feb 5, 2026; GPT-5.3 Codex came out Feb 5, 2026. Knowledge cutoff: Claude Opus 4.6 May 31, 2025, GPT-5.3 Codex Aug 31, 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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