Model comparison
Claude Fable 5 vs GPT-5.5 Pro
Anthropic against OpenAI, compared on context, price, and verified benchmark results.
Catalog record checked September 3, 2026Individual provider fields may changeEvidence confidence: High — see receipts below
Anthropic
Claude Fable 5
Frontier
OpenAI
GPT-5.5 Pro
Frontier
| Specification | Claude Fable 5 | GPT-5.5 Pro |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Tier | Frontier | Frontier |
| Context window | 1M | Winner: 1.05M |
| Max output | 128K | 128K |
| Input / 1M tokens | Winner: $10 | $30 |
| Output / 1M tokens | Winner: $50 | $180 |
| Weights | Closed | Closed |
| Parameters | Not disclosedUnverified | Not disclosedUnverified |
| Reasoning levels | adaptive | none, low, medium, high, xhigh, max |
| Modalities | text, image | text, image |
| API model id | claude-fable-5 | gpt-5.5-pro |
| Released | June 9, 2026 | April 23, 2026 |
| Artificial Analysis Intelligence Index (2026-08-14) | 62 | Not verifiedUnverified |
| Artificial Analysis Intelligence Index [xhigh] (2026-08-14) | Not verifiedUnverified | 60 |
Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Bold indicates the better figure where one is objectively better. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.
Benchmark receipts
- 2026-08-14: Artificial AnalysisComposite index blending reasoning, knowledge, and coding evals into one 0–100 score. Comparability: directly comparable — AA occasionally rebaselines the index scale between snapshots — a score captured on one date is only comparable to same-snapshot scores (check measuredAt).
Pricing tiers: Claude Fable 5: Standard $10/$50 per MTok; cache reads 10% of base input. Sibling Claude Mythos 5 is invite-only cyber-defense. Access briefly suspended 2026-06-12, redeployed 2026-07-01. · GPT-5.5 Pro: Standard $30/$180 per MTok; no cached-input discount. Batch $15/$90.
Claude Fable 5
Claude Fable 5 is Anthropic's next-generation intelligence model for long-running agents, topped LiveBench until the 5.1 refresh.
Best for
- Long-running agents
- Frontier reasoning
- Enterprise work
Watch out
Most expensive Anthropic tier at $10/$50; verify the cost is justified by the task.
GPT-5.5 Pro
GPT-5.5 Pro is OpenAI's highest-effort tier for maximal accuracy on the hardest tasks.
Best for
- Maximum-accuracy reasoning
- Research
- Hard enterprise workloads
Watch out
At $30/$180 per MTok it is the most expensive OpenAI tier; reserve for work that needs it.
When the cheaper one wins
Claude Fable 5 is cheaper on output at $50 per million tokens against $180 for GPT-5.5 Pro — about 3.6×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. These are standard-tier API rates, excluding batch and cache discounts.
Run the model pickerEvidence confidence: High
How strong and complete the evidence behind this comparison is — not a prediction of which model is better.
- Pricing verified on both sides — Input and output rates are verified for both models.
- 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
- 1 shared named benchmark with differing scores — Measured on: Artificial Analysis Intelligence Index.
- Verified within the last 90 days — Newest catalog check was 8 days ago.
- Both models carry source citations — Each side has at least two catalog sources on record.
Source receipts
Each catalog figure was checked against the provider or an independent second source on the date shown.
- Claude Fable 5: Anthropic — Claude Fable 5 (accessed 2026-08-29)
- Claude Fable 5: Anthropic news — Claude Fable 5 (accessed 2026-08-29)
- GPT-5.5 Pro: OpenAI — Introducing GPT-5.5 (accessed 2026-08-29)
- GPT-5.5 Pro: OpenAI API pricing (gpt-5.5-pro $30/$180) (accessed 2026-08-29)
Related comparisons
- Claude Fable 5.1 vs GPT-5.5 Pro
- Claude Fable 5 vs Claude Fable 5.1
- Claude Fable 5 vs Claude Haiku 4.5
- Claude Fable 5 vs Claude Mythos 5.1
- Claude Fable 5 vs Claude Opus 5
- Claude Fable 5 vs Claude Sonnet 5
Diving deeper on one model? Claude Fable 5 · GPT-5.5 Pro
Common questions
Claude Fable 5 vs GPT-5.5 Pro
Answered from the verified figures on this page rather than general guidance.
Is Claude Fable 5 or GPT-5.5 Pro cheaper for input?
Claude Fable 5 is cheaper at $10 per million input tokens, against $30 for GPT-5.5 Pro — roughly 3.0× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Claude Fable 5 has tiered pricing: Standard $10/$50 per MTok; cache reads 10% of base input. Sibling Claude Mythos 5 is invite-only cyber-defense. Access briefly suspended 2026-06-12, redeployed 2026-07-01. GPT-5.5 Pro has tiered pricing: Standard $30/$180 per MTok; no cached-input discount. Batch $15/$90.
Is Claude Fable 5 or GPT-5.5 Pro cheaper for output?
Claude Fable 5 is cheaper at $50 per million output tokens, against $180 for GPT-5.5 Pro — roughly 3.6× the price. Output tokens usually dominate a real bill, so weigh the output rate more heavily than the input rate. These are base rates; Claude Fable 5 has tiered pricing: Standard $10/$50 per MTok; cache reads 10% of base input. Sibling Claude Mythos 5 is invite-only cyber-defense. Access briefly suspended 2026-06-12, redeployed 2026-07-01. GPT-5.5 Pro has tiered pricing: Standard $30/$180 per MTok; no cached-input discount. Batch $15/$90.
Which has the larger context window, Claude Fable 5 or GPT-5.5 Pro?
GPT-5.5 Pro accepts 1.05M tokens against 1M for Claude Fable 5. This only matters if you routinely send very long documents or large codebases.
Do Claude Fable 5 and GPT-5.5 Pro support the same reasoning levels?
Claude Fable 5 exposes adaptive, while GPT-5.5 Pro exposes none, low, medium, high, xhigh, max.
Should I use Claude Fable 5 or GPT-5.5 Pro?
Both sit in the frontier tier, so the choice usually comes down to price and context rather than capability. Claude Fable 5 suits long-running agents; GPT-5.5 Pro suits maximum-accuracy reasoning.
Next step
Choosing between them
The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.
- Input price: Claude Fable 5 costs $10 per 1M tokens versus $30 for GPT-5.5 Pro — a 3x difference at the headline tier.
- Context: GPT-5.5 Pro takes 1.05M against 1M for Claude Fable 5 — only decisive if your prompts approach the smaller window.
Choosing a harness rather than a model — Cursor, Copilot, Claude Code, Windsurf, or Lovable? Compare agentic harnesses · Latest releases.