Head-to-head · Updated
Data verifiedClaude Fable 5 is the strongest coding model available: 80.3% SWE-Bench Pro vs GPT-5.5's 58.6% — a 21.7-point gap, and 1932 vs 1769 on GDPval-AA. GPT-5.5 is cheaper at $5/$30 vs $10/$50 and is the better fit when your stack is OpenAI-native (Codex, ChatGPT, computer-use). For raw coding and reasoning quality on new work, Fable 5 is the clear pick.
Claude Fable 5
New global #1 — 80.3% SWE-Bench Pro, the most capable model generally available.
WinnerGPT-5.5
Best OpenAI flagship for agentic coding, research, and computer-use work.
| Claude Fable 5 | GPT-5.5 | |
|---|---|---|
| Input cost / 1M tokens | $$10.00/1M | $$30.00/1M |
| Output cost / 1M tokens | $$50.00/1M | $$180.00/1M |
| Context window | 1M tokens | 1M tokens |
| Speed | Deliberate | Balanced |
| Price tier | Premium | Premium |
| Benchmarks | ||
| SWE-bench (coding) | 93.4% | — |
| Arena Elo | 1,932 | — |
| MMLU | 94.2% | — |
Which model wins for each use case — and why.
Fable 5 leads SWE-Bench Pro 80.3% vs 58.6% — the widest gap between any two frontier coding models today.
GPT-5.5 is cheaper on output ($5/$30 vs $10/$50) and a better value when you don't need Fable 5's ceiling.
GPT-5.5 wins when you depend on Codex, ChatGPT rollout, OpenAI APIs, or OpenAI-native computer-use agents.
Fable 5 scores 1932 on GDPval-AA vs GPT-5.5's 1769 — a large head-to-head preference margin.
Both support a 1M-token API context window.
Fable 5's Mythos-class reasoning and native parallel subagents handle longer autonomous loops more reliably.
Pick Claude Fable 5 if…
Pick GPT-5.5 if…
Bottom line
For most workflows, Claude Fable 5 is the stronger choice.
The strongest coding and reasoning model you can actually use today. 80.3% SWE-Bench Pro is an 11-point leap over Opus 4.8 — the biggest single-release jump of 2026. It costs 2× Opus 4.8, so use it for the hardest agentic and engineering work and keep Opus 4.8 or Sonnet for everyday volume.
Is Claude Fable 5 or GPT-5.5 better for coding?
Claude Fable 5, decisively. It scores 80.3% on SWE-Bench Pro vs GPT-5.5's 58.6% — a 21.7-point lead, the largest gap between any two frontier coding models currently available.
Which is cheaper, Fable 5 or GPT-5.5?
GPT-5.5 is cheaper at $5 input / $30 output per 1M tokens vs Fable 5's $10 / $50. If cost matters more than the coding ceiling, GPT-5.5 — or Claude Opus 4.8 at $5/$25 — is the better value.
When should I pick GPT-5.5 over Fable 5?
Choose GPT-5.5 when your stack is OpenAI-native: Codex integrations, ChatGPT deployment, OpenAI function-calling agents, or computer-use workflows built on OpenAI's tooling.
Do both models have a 1M-token context window?
Yes. Both Claude Fable 5 and GPT-5.5 support a 1M-token API context window, so either can handle large codebases and document sets in a single request.
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