Claude Fable 5 vs GPT-5.5
Side-by-side comparison of pricing, context window, modalities, licensing, and strengths — with practical guidance on which model fits which workload.
| Spec | Claude Fable 5 | GPT-5.5 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Context window | 1M tokens | 1M tokens |
| Input price (per 1M tokens) | $10.00 | $5.00 |
| Output price (per 1M tokens) | $50.00 | $30.00 |
| Example workload (10M in + 2M out) | $200.00 / month | $110.00 / month |
| Modalities | text, image, code | text, image, audio, code |
| Knowledge cutoff | Jan 2026 | Not disclosed |
| Release date | 2026 | 2026 |
| License | Proprietary | Proprietary |
| Strengths | Deepest reasoning, Long-horizon agents, Writing, 1M context | Flagship reasoning, Agentic tool use, Multimodal, Coding |
| Open weights | No | No |
Verdict
The premium-tier showdown. Claude Fable 5 sits above Anthropic’s own Opus line at $10/$50 per million tokens, built for the hardest reasoning and long-horizon agentic work — with always-on adaptive thinking and single requests that can run many minutes on hard tasks. GPT-5.5 is cheaper at $5/$30 and more versatile (audio in, huge ecosystem), but Fable 5 targets the depth ceiling: multi-hour autonomous runs, first-shot implementations of well-specified systems, and end-to-end knowledge-work deliverables.
When to choose Claude Fable 5
Pick Claude Fable 5 when correctness on the hardest problems justifies premium pricing — deep research, complex system builds, long autonomous runs.
When to choose GPT-5.5
Pick GPT-5.5 for versatile flagship work at half the output price, audio modality, and lower-latency interactive use.
Prices and specs reflect published provider information and change frequently — always confirm on the provider's pricing page before committing to a workload.
About
This page compares Claude Fable 5 (Anthropic) and GPT-5.5 (OpenAI) side by side across the specs that actually drive a model decision: API pricing per million tokens, context window size, supported modalities, licensing and open-weights status, knowledge cutoff, and headline strengths. A worked example projects the monthly cost of a typical workload (10M input + 2M output tokens) on each model, and an editorial verdict summarises when to choose which. Spec data comes from the same registry that powers our full model comparison table, so figures stay consistent across the site.
How to use
- 1 Scan the spec table for the head-to-head numbers — pricing, context window, modalities, license, and strengths for Claude Fable 5 and GPT-5.5.
- 2 Check the example-workload row to see what a realistic monthly volume costs on each model.
- 3 Read the verdict and the two "when to choose" cards to map each model to your use case.
- 4 Use the FAQ for quick answers on price, context window, and self-hosting.
- 5 Estimate your own numbers with the AI cost calculator and token counter linked at the bottom, or jump to a related comparison.
- Which is cheaper: Claude Fable 5 or GPT-5.5?
- GPT-5.5 is cheaper per token: $5.00 input / $30.00 output per 1M tokens, versus $10.00 / $50.00 for Claude Fable 5. Actual costs depend on your input-to-output ratio — try the AI cost calculator for your own numbers.
- Which has the larger context window?
- Both models offer roughly the same 1M-token context window, so raw capacity won't be the deciding factor — check instead whether either provider charges premium rates for long prompts.
- Can I self-host either model?
- No — both models are proprietary and available only through their providers' APIs or cloud platforms.
- How should I test which model is better for my use case?
- Benchmarks are a starting point, not an answer. Run both models on 20–50 examples of your real task and compare outputs blind. Use our token counter to estimate prompt sizes and the cost calculator to project monthly spend before committing.
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