Head-to-head comparison across 4benchmark categories. Overall scores shown here use BenchLM's provisional ranking lane.
Claude Fable 5
96
GPT-5.5
90
Verified leaderboard positions: Claude Fable 5 #2 · GPT-5.5 #7
Pick Claude Fable 5 if you want the stronger benchmark profile. GPT-5.5 only becomes the better choice if you want the cheaper token bill.
Agentic
+3.7 difference
Coding
+27.0 difference
Knowledge
+8.4 difference
Multimodal
+22.0 difference
Claude Fable 5
GPT-5.5
$10 / $50
$5 / $30
N/A
N/A
N/A
N/A
1M+
1M
Pick Claude Fable 5 if you want the stronger benchmark profile. GPT-5.5 only becomes the better choice if you want the cheaper token bill.
Claude Fable 5 is clearly ahead on the provisional aggregate, 96 to 90. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Fable 5's sharpest advantage is in coding, where it averages 85.6 against 58.6. The single biggest benchmark swing on the page is SWE-bench Pro, 80% to 58.6%.
Claude Fable 5 is also the more expensive model on tokens at $10.00 input / $50.00 output per 1M tokens, versus $5.00 input / $30.00 output per 1M tokens for GPT-5.5. Claude Fable 5 gives you the larger context window at 1M+, compared with 1M for GPT-5.5.
Claude Fable 5 is ahead on BenchLM's provisional leaderboard, 96 to 90. The biggest single separator in this matchup is SWE-bench Pro, where the scores are 80% and 58.6%.
Claude Fable 5 has the edge for knowledge tasks in this comparison, averaging 74.8 versus 66.4. Inside this category, HLE w/o tools is the benchmark that creates the most daylight between them.
Claude Fable 5 has the edge for coding in this comparison, averaging 85.6 versus 58.6. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.
Claude Fable 5 has the edge for agentic tasks in this comparison, averaging 85.2 versus 81.5. Inside this category, GDPval-AA is the benchmark that creates the most daylight between them.
Claude Fable 5 has the edge for multimodal and grounded tasks in this comparison, averaging 92.4 versus 70.4. Inside this category, MMMU-Pro 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.