GPT-5.3 Codex vs GPT-6 Sol vs Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview comes out ahead, 52 to 47 and 42 on our weighted score, though GPT-6 Sol is 11% cheaper per token.
OpenAIGPT-5.3 Codex
42/100- ECI156.8
- Price$1.75 / $14.00
- Context400K
- OpenAI
GPT-6 Sol
47/100- ECI—
- Price$2.00 / $10.00
- Context1.05M
- Our pick
GoogleGemini 3.1 Pro Preview
52/100- 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 52/100 against GPT-6 Sol (47) and GPT-5.3 Codex (42). It leads on inputs & features. GPT-6 Sol wins on price. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
- CapabilityNot enough dataNo independent benchmark covers every model here yet
- Lowest priceGPT-6 SolGPT-6 Sol $4.00 · Gemini 3.1 Pro Preview $4.50 · GPT-5.3 Codex $4.81 per 1M tokens (3:1 blend)
- Longest contextGPT-6 Sol and Gemini 3.1 Pro PreviewGPT-6 Sol 1,050,000 · Gemini 3.1 Pro Preview 1,048,576 · GPT-5.3 Codex 400,000 tokens
- Widest inputsGemini 3.1 Pro PreviewGPT-5.3 Codex: Text, Images, PDFs · GPT-6 Sol: 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 | GPT-6 Sol | Gemini 3.1 Pro Preview |
|---|---|---|---|---|
| Price | 50% | 18 | 21 | 19 |
| Inputs & features | 30% | 80 | 80 | 100 |
| Context window | 20% | 44 | 61 | 61 |
| Overall | 100% | 42/100 | 47/100 | 52/100 |
Left out because at least one model lacks the data: capability. The remaining weights were rescaled.
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.3 CodexOpenAI | GPT-6 SolOpenAI | Gemini 3.1 Pro PreviewGoogle |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 156.8 (best) | — | 154.8 |
| ECI rank | #18 of 148 (best) | — | #31 of 148 |
| GPQA DiamondGraduate-level science questions | — | 94.3% | 94.4% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | — | 89.8% (best) | 59.7% |
| OTIS Mock AIME 2024–2025Competition mathematics | — | 100% (best) | 95.6% |
| SWE-bench VerifiedFixing real GitHub issues | 74.8% | — | 75.6% (best) |
| SimpleQA VerifiedShort factual questions | — | 60.7% | 73.5% (best) |
| Price per million tokens | |||
| Input | $1.75 (best) | $2.00 | $2.00 |
| Output | $14.00 | $10.00 (best) | $12.00 |
| Cached input | $0.175 (best) | $0.20 | $0.20 |
| Blended (3:1) | $4.81 | $4.00 (best) | $4.50 |
| Long-context rate | Same rate | Over 272K: $4.00 / $15.00 | Over 200K: $4.00 / $18.00 |
| Price source | Official OpenAI API | Official OpenAI API | Official Google API |
| Limits | |||
| Context window | 400,000 tokens | 1,050,000 tokens (best) | 1,048,576 tokens |
| 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 · xhigh | Yeslow · medium · high · xhigh · 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 | gpt-6-sol | gemini-3.1-pro-preview |
| API providers | 19 | 25 | 26 (best) |
| Released | Feb 5, 2026 | Sep 22, 2026 | Feb 19, 2026 |
| Knowledge cutoff | Aug 31, 2025 | Apr 20, 2026 | 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
- GPT-6 Sol$40.00
- Gemini 3.1 Pro Preview$44.00
Which should you choose?
Which is better: GPT-5.3 Codex, GPT-6 Sol or Gemini 3.1 Pro Preview?
Gemini 3.1 Pro Preview is the better all-round choice, scoring 52/100 against GPT-6 Sol (47) and GPT-5.3 Codex (42). It leads on inputs & features. GPT-6 Sol wins on price. The score weighs price 50%, inputs & features 30%, context window 20%. None of the shared benchmarks cover every model here yet, so capability is left out of this verdict.
Which is cheaper, GPT-5.3 Codex, GPT-6 Sol or Gemini 3.1 Pro Preview?
GPT-6 Sol is cheaper at $2.00 input / $10.00 output per million tokens (official OpenAI API price). 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 $4.00 per million tokens for GPT-6 Sol versus $4.50 for Gemini 3.1 Pro Preview (1.1× as much) and $4.81 for GPT-5.3 Codex (1.2× as much).
Which scores higher on benchmarks?
There is no independent benchmark that covers all three models yet. GPT-5.3 Codex has an ECI of 156.8, GPT-6 Sol has not been scored yet and Gemini 3.1 Pro Preview has an ECI of 154.8.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-6 Sol yet, so there is no like-for-like coding score. Test both on a sample of your own tasks. All three support tool calling for agent workflows.
Which has the bigger context window?
GPT-6 Sol and Gemini 3.1 Pro Preview have the largest context windows (1,050,000 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, GPT-6 Sol up to 128,000, 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; GPT-6 Sol 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, GPT-6 Sol and Gemini 3.1 Pro Preview are proprietary and only available through APIs and apps.
Which is newer?
GPT-6 Sol is the newest, released Sep 22, 2026. Gemini 3.1 Pro Preview came out Feb 19, 2026; GPT-5.3 Codex came out Feb 5, 2026. Knowledge cutoff: GPT-5.3 Codex Aug 31, 2025, GPT-6 Sol Apr 20, 2026, 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.
