Claude Sonnet 4.5 vs Gemma 4 31B

Pick Claude Sonnet 4.5 if you want the stronger benchmark profile. Gemma 4 31B only becomes the better choice if you want the cheaper token bill or you need the larger 256K context window.

Claude Sonnet 4.5 finishes one point ahead on BenchLM's provisional leaderboard, 66 to 65. That is enough to call, but not enough to treat as a blowout. This matchup comes down to a few meaningful edges rather than one model dominating the board.

Claude Sonnet 4.5's sharpest advantage is in coding, where it averages 77.2 against 41.6. The single biggest benchmark swing on the page is GPQA, 83.4% to 84.3%.

Claude Sonnet 4.5 is also the more expensive model on tokens at $3.00 input / $15.00 output per 1M tokens, versus $0.00 input / $0.00 output per 1M tokens for Gemma 4 31B. That is roughly Infinityx on output cost alone. Gemma 4 31B is the reasoning model in the pair, while Claude Sonnet 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. Gemma 4 31B gives you the larger context window at 256K, compared with 200K for Claude Sonnet 4.5.