GPT-5.3 Codex vs Claude Sonnet 4.6 vs Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview comes out ahead, 68 to 64 and 62 on our weighted score, and it is the cheaper option too.
OpenAIGPT-5.3 Codex
64/100- ECI156.8
- Price$1.75 / $14.00
- Context400K
AnthropicClaude Sonnet 4.6
62/100- ECI152.3
- Price$3.00 / $15.00
- Context1M
- 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 Sonnet 4.6 (62). 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 · Gemini 3.1 Pro Preview 154.8 · Claude Sonnet 4.6 152.3
- Lowest priceGemini 3.1 Pro PreviewGemini 3.1 Pro Preview $4.50 · GPT-5.3 Codex $4.81 · Claude Sonnet 4.6 $6.00 per 1M tokens (3:1 blend)
- Longest contextGemini 3.1 Pro PreviewGemini 3.1 Pro Preview 1,048,576 · Claude Sonnet 4.6 1,000,000 · GPT-5.3 Codex 400,000 tokens
- Widest inputsGemini 3.1 Pro PreviewGPT-5.3 Codex: Text, Images, PDFs · Claude Sonnet 4.6: 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 | GPT-5.3 Codex | Claude Sonnet 4.6 | Gemini 3.1 Pro Preview |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 87 | 81 | 84 |
| Price | 25% | 18 | 13 | 19 |
| Inputs & features | 15% | 80 | 80 | 100 |
| Context window | 10% | 44 | 60 | 61 |
| Overall | 100% | 64/100 | 62/100 | 68/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.3 CodexOpenAI | Claude Sonnet 4.6Anthropic | Gemini 3.1 Pro PreviewGoogle |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 156.8 (best) | 152.3 | 154.8 |
| ECI rank | #18 of 148 (best) | #40 of 148 | #31 of 148 |
| GPQA DiamondGraduate-level science questions | — | 87.4% | 94.4% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | — | — | 59.7% |
| OTIS Mock AIME 2024–2025Competition mathematics | — | 85.8% | 95.6% (best) |
| SWE-bench VerifiedFixing real GitHub issues | 74.8% | 75.2% | 75.6% (best) |
| SimpleQA VerifiedShort factual questions | — | 35.5% | 73.5% (best) |
| Price per million tokens | |||
| Input | $1.75 (best) | $3.00 | $2.00 |
| Output | $14.00 | $15.00 | $12.00 (best) |
| Cached input | $0.175 (best) | $0.30 | $0.20 |
| Blended (3:1) | $4.81 | $6.00 | $4.50 (best) |
| Long-context rate | Same rate | Same rate | Over 200K: $4.00 / $18.00 |
| Price source | Official OpenAI API | Official Anthropic API | Official Google API |
| Limits | |||
| Context window | 400,000 tokens | 1,000,000 tokens | 1,048,576 tokens (best) |
| Max output | 128,000 tokens (best) | 64,000 tokens | 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 · xhigh | Yeslow · medium · high · max | Yeslow · medium · high |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | gpt-5.3-codex | claude-sonnet-4-6 | gemini-3.1-pro-preview |
| API providers | 19 | 41 (best) | 26 |
| Released | Feb 5, 2026 | Feb 17, 2026 | Feb 19, 2026 |
| Knowledge cutoff | Aug 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.
- GPT-5.3 Codex$45.50
- Claude Sonnet 4.6$60.00
- Gemini 3.1 Pro Preview$44.00
Which should you choose?
Which is better: GPT-5.3 Codex, Claude Sonnet 4.6 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 Sonnet 4.6 (62). 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, GPT-5.3 Codex, Claude Sonnet 4.6 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 Sonnet 4.6 costs $3.00 input / $15.00 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 $6.00 for Claude Sonnet 4.6 (1.3× 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), Gemini 3.1 Pro Preview 154.8 (#31 of 148) and Claude Sonnet 4.6 152.3 (#40 of 148). The confidence ranges of the top two overlap (153.5–160.8 vs 152.6–157.3), so treat the gap as small. On individual benchmarks: SWE-bench Verified — Gemini 3.1 Pro Preview 75.6%, Claude Sonnet 4.6 75.2%, GPT-5.3 Codex 74.8%.
Which is better for coding?
Gemini 3.1 Pro Preview resolves more real GitHub issues on SWE-bench Verified: Gemini 3.1 Pro Preview 75.6%, Claude Sonnet 4.6 75.2% 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 Sonnet 4.6 and 400,000 for GPT-5.3 Codex. Maximum output per response: GPT-5.3 Codex up to 128,000, Claude Sonnet 4.6 up to 64,000, Gemini 3.1 Pro Preview up to 65,536 tokens.
Which can read images, PDFs, audio or video?
GPT-5.3 Codex accepts text, images and PDFs; Claude Sonnet 4.6 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-5.3 Codex, Claude Sonnet 4.6 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 Sonnet 4.6 came out Feb 17, 2026; GPT-5.3 Codex came out Feb 5, 2026. Knowledge cutoff: GPT-5.3 Codex Aug 31, 2025, Claude Sonnet 4.6 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.
Related comparisons
- GPT-5.3 Codex vs Claude Sonnet 5Anthropic · ECI 156.3
- GPT-5.3 Codex vs Kimi K3Moonshot AI · ECI 157.6
- GPT-5.3 Codex vs Qwen3.8 MaxAlibaba (Qwen) · ECI 156.6
- Claude Sonnet 4.6 vs GPT-5.2OpenAI · ECI 153.5
- Claude Sonnet 4.6 vs Gemini 3 Pro PreviewGoogle · ECI 153.0
- Claude Sonnet 4.6 vs Qwen3.7 MaxAlibaba (Qwen) · ECI 153.7
