GPT-5.2 Codex vs GPT-6.1 Sol
Different efforts: xhigh · medium · Compare all at xhigh
Humanity's Last Exam Humanity's Last Exam: Very hard expert questions across many fields, written to stump today’s models
GPT-5.2 Codex35.7
GPT-6.1 Sol49.9
Terminal-Bench 4.0 Terminal-Bench 4.0 · source setting 2: Agents use a terminal to complete executable coding, system administration and research tasks in the 4.0 suite
GPT-5.2 Codex—
GPT-6.1 Sol48
AutomationBench-AA AutomationBench-AA: Agents orchestrate SaaS workflows through APIs; objectives receive credit only when the task has no guardrail violation
GPT-5.2 Codex—
GPT-6.1 Sol62.6
Arena Text · creative writing Arena Text · creative writing: Human pairwise preferences in the stated text vote pool
GPT-5.2 Codex—
GPT-6.1 Sol · max1,458
MMMU-Pro (vision) MMMU-Pro (vision): College-level questions that require understanding images: charts, diagrams, photos
GPT-5.2 Codex76.3
GPT-6.1 Sol83.9
| Benchmark | GPT-5.2 Codex | GPT-6.1 Sol |
|---|---|---|
| Humanity's Last Exam | 35.7 | 49.9 |
| Terminal-Bench 4.0 | — | 48 |
| AutomationBench-AA | — | 62.6 |
| Arena Text · creative writing | — | 1,458 · max |
| MMMU-Pro (vision) | 76.3 | 83.9 |
Specs
| Spec | GPT-5.2 Codex | GPT-6.1 Sol |
|---|---|---|
| Input, per 1M | $1.75 | $2 |
| Output, per 1M | $14 | $10 |
| Cost per task? | — | $0.21 |
| Speed, tok/s | 121 | 45 |
| Context | 400K | 1.05M |
| Weights | Closed | Closed |
| Released | Dec 2025 | Sep 2026 |
| See images | ✓ | ✓ |
| Read PDFs | Partial | Partial |
| Hear audio | — | — |
| Watch video | — | — |
| Call tools | ✓ | ✓ |
| Force a tool call | Partial | Partial |
| Return strict JSON | ✓ | ✓ |
| Search the web | ? | ✓ |
| Run code | ? | ✓ |
| Use a computer | ? | ✓ |
What breaks when you switch
GPT-5.2 Codex → GPT-6.1 Sol
Remove unsupported parameters›
With reasoning enabled, remove temperature, top_p and top_logprobs, plus Chat Completions logprobs or Responses message.output_text.logprobs includes.
Responses API for tool calling · Chat Completions›
Use Responses for tools; Chat Completions supports this model without tool calling.
No none or minimal reasoning›
The none and minimal reasoning efforts are unsupported; choose low, medium, high, xhigh or max.
More than 272K input tokens›
Prompts above 272K input tokens charge 2× input and cache rates and 1.5× output rates for the entire request.
Cache writes billed at 1.25x›
Cache writes cost 1.25× the uncached input token rate.
Ultrafast prices 6x Standard›
Ultrafast mode costs 6× Standard token prices.
GPT-6.1 Sol → GPT-5.2 Codex
Context: 1.05M → 400K
Deprecated›
The official model page marks this model deprecated; plan a migration.