Gemini 3.8 Flash vs GPT-6.1 Sol
MMMU-Pro (vision) MMMU-Pro (vision): College-level questions that require understanding images: charts, diagrams, photos
Gemini 3.8 Flash84.2
GPT-6.1 Sol83.9
GDP.pdf · AA all-pass GDP.pdf · AA all-pass: Models reason over professional PDF documents; an attempt passes only when every atomic criterion passes
Gemini 3.8 Flash22.8
GPT-6.1 Sol30
Arena Vision · overall Arena Vision · overall: Human pairwise preferences in the stated vision vote pool
Gemini 3.8 Flash · high1,315.4
GPT-6.1 Sol · max1,287.7
Chartography Chartography: Expert chart reasoning over professional scientific, medical, financial and engineering charts
Gemini 3.8 Flash · high40.9
GPT-6.1 Sol—
| Benchmark | Gemini 3.8 Flash | GPT-6.1 Sol |
|---|---|---|
| MMMU-Pro (vision) | 84.2 | 83.9 |
| GDP.pdf · AA all-pass | 22.8 | 30 |
| Arena Vision · overall | 1,315.4 · high | 1,287.7 · max |
| Chartography | 40.9 · high | — |
Specs
| Spec | Gemini 3.8 Flash | GPT-6.1 Sol |
|---|---|---|
| Input, per 1M | !$0.75 | $2 |
| Output, per 1M | !$3.75 | $10 |
| Cost per task? | $0.93 | $0.21 |
| Speed, tok/s | — | 45 |
| Context | 1M | 1.05M |
| Weights | Closed | Closed |
| Released | Sep 2026 | Sep 2026 |
| See images | ✓ | ✓ |
| Read PDFs | ✓ | 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
Gemini 3.8 Flash → 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 → Gemini 3.8 Flash
Context: 1.05M → 1M
Sampling parameters are ignored›
temperature, top_p and top_k are ignored now and will cause HTTP 400 in future generations; remove them from requests.
No minimal thinking level›
The minimal thinking level returns an error; avoid minimal.