GPT-5.5 vs GPT-6.1 Sol
| Benchmark | GPT-5.5 | GPT-6.1 Sol |
|---|---|---|
| Humanity's Last Exam | 42.4 | 49.9 |
| Terminal-Bench 4.0 | 5.1 | 48 |
| AutomationBench-AA | 40.1 | 62.6 |
| MMMU-Pro (vision) | 81.2 | 83.9 |
Specs
| Spec | GPT-5.5 | GPT-6.1 Sol |
|---|---|---|
| Input, per 1M | $5 | $2 |
| Output, per 1M | $30 | $10 |
| Cost per task? | $0.77 | $0.21 |
| Speed, tok/s | 82 | 52 |
| Context | 1.05M | 1.05M |
| Weights | Closed | Closed |
| Released | Apr 2026 | 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-5.5 → 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-5.5
Prompts with >272K input tokens›
Above 272K input tokens, input costs 2× and output 1.5× for the full session in Standard, Batch and Flex.