Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Composer 2.5
82
GPT-5.3 Codex
87
Pick GPT-5.3 Codex if you want the stronger benchmark profile. Composer 2.5 only becomes the better choice if you want the cheaper token bill.
Agentic
+2.2 difference
Composer 2.5
GPT-5.3 Codex
$0.5 / $2.5
$1.75 / $14
N/A
79 t/s
N/A
88.26s
200K
400K
Pick GPT-5.3 Codex if you want the stronger benchmark profile. Composer 2.5 only becomes the better choice if you want the cheaper token bill.
GPT-5.3 Codex is clearly ahead on the provisional aggregate, 87 to 82. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
GPT-5.3 Codex's sharpest advantage is in agentic, where it averages 71.5 against 69.3. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 69.3% to 77.3%.
GPT-5.3 Codex is also the more expensive model on tokens at $1.75 input / $14.00 output per 1M tokens, versus $0.50 input / $2.50 output per 1M tokens for Composer 2.5. That is roughly 5.6x on output cost alone. GPT-5.3 Codex gives you the larger context window at 400K, compared with 200K for Composer 2.5.
GPT-5.3 Codex is ahead on BenchLM's provisional leaderboard, 87 to 82. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 69.3% and 77.3%.
GPT-5.3 Codex has the edge for agentic tasks in this comparison, averaging 71.5 versus 69.3. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
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