Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
GPT-5.3 Codex
85
Mistral Medium 3.5 128B
78
Pick GPT-5.3 Codex if you want the stronger benchmark profile. Mistral Medium 3.5 128B only becomes the better choice if coding is the priority or you want the cheaper token bill.
Coding
+14.5 difference
GPT-5.3 Codex
Mistral Medium 3.5 128B
$1.75 / $14
$1.5 / $7.5
79 t/s
N/A
88.26s
N/A
400K
256K
Pick GPT-5.3 Codex if you want the stronger benchmark profile. Mistral Medium 3.5 128B only becomes the better choice if coding is the priority or you want the cheaper token bill.
GPT-5.3 Codex is clearly ahead on the provisional aggregate, 85 to 78. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.3 Codex is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $1.50 input / $7.50 output per 1M tokens for Mistral Medium 3.5 128B. GPT-5.3 Codex gives you the larger context window at 400K, compared with 256K for Mistral Medium 3.5 128B.
GPT-5.3 Codex is ahead on BenchLM's provisional leaderboard, 85 to 78. The biggest single separator in this matchup is SWE-bench Verified, where the scores are 85% and 77.6%.
Mistral Medium 3.5 128B has the edge for coding in this comparison, averaging 77.6 versus 63.1. Inside this category, Terminal-Bench Hard is the benchmark that creates the most daylight between them.
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