Claude Sonnet 4.6 vs GPT-5.5

Pick GPT-5.5 if you want the stronger benchmark profile. Claude Sonnet 4.6 only becomes the better choice if coding is the priority or you want the cheaper token bill.

GPT-5.5 is clearly ahead on the provisional aggregate, 91 to 83. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.

GPT-5.5's sharpest advantage is in agentic, where it averages 81.5 against 65.1. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 59.1% to 82%. Claude Sonnet 4.6 does hit back in coding, so the answer changes if that is the part of the workload you care about most.

GPT-5.5 is also the more expensive model on tokens at $5.00 input / $30.00 output per 1M tokens, versus $3.00 input / $15.00 output per 1M tokens for Claude Sonnet 4.6. That is roughly 2.0x on output cost alone. GPT-5.5 is the reasoning model in the pair, while Claude Sonnet 4.6 is not. That usually helps on harder chain-of-thought-heavy tests, but it can also mean more latency and more token spend in real use. GPT-5.5 gives you the larger context window at 1M, compared with 200K for Claude Sonnet 4.6.