GPT-5.3 Codex vs Gemini 3 Pro Preview vs Gemini 3.1 Pro Preview
Too close to call on our weighted score (Gemini 3.1 Pro Preview 68, Gemini 3 Pro Preview 67, GPT-5.3 Codex 64). The right pick depends on what you value most.
OpenAIGPT-5.3 Codex
64/100- ECI156.8
- Price$1.75 / $14.00
- Context400K
GoogleGemini 3 Pro Preview
67/100- ECI153.0
- Price$2.00 / $12.00
- 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 3.1 Pro Preview 68/100, Gemini 3 Pro Preview 67/100, GPT-5.3 Codex 64/100), so choose by what matters most for your work: GPT-5.3 Codex for raw capability and Gemini 3 Pro Preview on price. 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 · Gemini 3 Pro Preview 153.0
- Lowest priceGemini 3 Pro Preview and Gemini 3.1 Pro PreviewGemini 3 Pro Preview $4.50 · Gemini 3.1 Pro Preview $4.50 · GPT-5.3 Codex $4.81 per 1M tokens (3:1 blend)
- Longest contextGemini 3 Pro Preview and Gemini 3.1 Pro PreviewGemini 3 Pro Preview 1,048,576 · Gemini 3.1 Pro Preview 1,048,576 · GPT-5.3 Codex 400,000 tokens
- Widest inputsGemini 3 Pro Preview and Gemini 3.1 Pro PreviewGPT-5.3 Codex: Text, Images, PDFs · Gemini 3 Pro Preview: 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 | GPT-5.3 Codex | Gemini 3 Pro Preview | Gemini 3.1 Pro Preview |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 87 | 82 | 84 |
| Price | 25% | 18 | 19 | 19 |
| Inputs & features | 15% | 80 | 100 | 100 |
| Context window | 10% | 44 | 61 | 61 |
| Overall | 100% | 64/100 | 67/100 | 68/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.3 CodexOpenAI | Gemini 3 Pro PreviewGoogle | Gemini 3.1 Pro PreviewGoogle |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 156.8 (best) | 153.0 | 154.8 |
| ECI rank | #18 of 148 (best) | #39 of 148 | #31 of 148 |
| GPQA DiamondGraduate-level science questions | — | 92.6% | 94.4% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | — | — | 59.7% |
| OTIS Mock AIME 2024–2025Competition mathematics | — | 91.4% | 95.6% (best) |
| SWE-bench VerifiedFixing real GitHub issues | 74.8% | 72.9% | 75.6% (best) |
| SimpleQA VerifiedShort factual questions | — | — | 73.5% |
| Price per million tokens | |||
| Input | $1.75 (best) | $2.00 | $2.00 |
| Output | $14.00 | $12.00 (best) | $12.00 (best) |
| Cached input | $0.175 (best) | — | $0.20 |
| Blended (3:1) | $4.81 | $4.50 (best) | $4.50 (best) |
| Long-context rate | Same rate | Same rate | Over 200K: $4.00 / $18.00 |
| Price source | Official OpenAI API | Median of 2 providers | Official Google API |
| Limits | |||
| Context window | 400,000 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 · xhigh | Yes | 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 | — | gemini-3.1-pro-preview |
| API providers | 19 | 3 | 26 (best) |
| Released | Feb 5, 2026 | Nov 18, 2025 | Feb 19, 2026 |
| Knowledge cutoff | Aug 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.
- GPT-5.3 Codex$45.50
- Gemini 3 Pro Preview$44.00
- Gemini 3.1 Pro Preview$44.00
Which should you choose?
Which is better: GPT-5.3 Codex, Gemini 3 Pro Preview or Gemini 3.1 Pro Preview?
It is close. Our weighted score puts them within 1 points (Gemini 3.1 Pro Preview 68/100, Gemini 3 Pro Preview 67/100, GPT-5.3 Codex 64/100), so choose by what matters most for your work: GPT-5.3 Codex for raw capability and Gemini 3 Pro Preview on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-5.3 Codex, Gemini 3 Pro Preview or Gemini 3.1 Pro Preview?
Gemini 3 Pro Preview is cheaper at $2.00 input / $12.00 output per million tokens (median across 2 API providers). Gemini 3.1 Pro Preview costs $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). At a typical mix of three input tokens to one output token, that is $4.50 per million tokens for Gemini 3 Pro Preview versus $4.50 for Gemini 3.1 Pro Preview (1× as much) and $4.81 for GPT-5.3 Codex (1.1× 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 Gemini 3 Pro Preview 153.0 (#39 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%, GPT-5.3 Codex 74.8%, Gemini 3 Pro Preview 72.9%.
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%, GPT-5.3 Codex 74.8% and Gemini 3 Pro Preview 72.9%. All three support tool calling for agent workflows.
Which has the bigger context window?
Gemini 3 Pro Preview and Gemini 3.1 Pro Preview have the largest context windows (1,048,576 and 1,048,576 tokens), against 400,000 for GPT-5.3 Codex. Maximum output per response: GPT-5.3 Codex up to 128,000, Gemini 3 Pro Preview up to 65,536, 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; Gemini 3 Pro Preview accepts text, images, PDFs, audio and video; Gemini 3.1 Pro Preview accepts text, images, PDFs, audio and video. Gemini 3 Pro Preview handles the widest range of inputs.
Are any of these open source?
No. GPT-5.3 Codex, Gemini 3 Pro Preview 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. GPT-5.3 Codex came out Feb 5, 2026; Gemini 3 Pro Preview came out Nov 18, 2025. Knowledge cutoff: GPT-5.3 Codex Aug 31, 2025, Gemini 3 Pro Preview 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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