Head-to-head comparison across 1benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Composer 2.5
82
GPT-5.5
91
Verified leaderboard positions: Composer 2.5 unranked · GPT-5.5 #4
Pick GPT-5.5 if you want the stronger benchmark profile. Composer 2.5 only becomes the better choice if you want the cheaper token bill.
Agentic
+12.2 difference
Composer 2.5
GPT-5.5
$0.5 / $2.5
$5 / $30
N/A
N/A
N/A
N/A
200K
1M
Pick GPT-5.5 if you want the stronger benchmark profile. Composer 2.5 only becomes the better choice if you want the cheaper token bill.
GPT-5.5 is clearly ahead on the provisional aggregate, 91 to 82. 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 69.3. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 69.3% to 82%.
GPT-5.5 is also the more expensive model on tokens at $5.00 input / $30.00 output per 1M tokens, versus $0.50 input / $2.50 output per 1M tokens for Composer 2.5. That is roughly 12.0x on output cost alone. GPT-5.5 gives you the larger context window at 1M, compared with 200K for Composer 2.5.
GPT-5.5 is ahead on BenchLM's provisional leaderboard, 91 to 82. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 69.3% and 82%.
GPT-5.5 has the edge for agentic tasks in this comparison, averaging 81.5 versus 69.3. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
For engineers, researchers, and the plain curious — a weekly brief on new models, ranking shifts, and pricing changes.
Free. No spam. Unsubscribe anytime.