Claude Opus 4.5 vs GLM-5.1

Pick Claude Opus 4.5 if you want the stronger benchmark profile. GLM-5.1 only becomes the better choice if agentic is the priority or you want the cheaper token bill.

Claude Opus 4.5 has the cleaner provisional overall profile here, landing at 76 versus 74. It is a real lead, but still close enough that category-level strengths matter more than the headline number.

Claude Opus 4.5's sharpest advantage is in knowledge, where it averages 66.2 against 52.3. The single biggest benchmark swing on the page is HLE, 30.8% to 52.3%. GLM-5.1 does hit back in agentic, so the answer changes if that is the part of the workload you care about most.

Claude Opus 4.5 is also the more expensive model on tokens at $5.00 input / $25.00 output per 1M tokens, versus $1.40 input / $4.40 output per 1M tokens for GLM-5.1. That is roughly 5.7x on output cost alone. GLM-5.1 is the reasoning model in the pair, while Claude Opus 4.5 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. GLM-5.1 gives you the larger context window at 203K, compared with 200K for Claude Opus 4.5.