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Claude Fable 5 vs GPT-5.5
Price, context window and capabilities side by side — read from the same catalog that meters your calls, not from a press release.
GPT-5.5 is 2.0x cheaper on input. GPT-5.5 is 1.7x cheaper on output. GPT-5.5 holds 256K tokens against 200K.
At a glance
Side by side
Anthropic
Anthropic's first Mythos-class model, the new flagship tier above Opus, tuned for the hardest reasoning and agentic work.
Specifications
Every difference we can measure
| Claude Fable 5 | GPT-5.5 | |
|---|---|---|
| Input price | $10/M | $5/M |
| Output price | $50/M | $30/M |
| Context window | 200K tokens | 256K tokens |
| Vision | Yes | Yes |
| Tool calling | Yes | Yes |
A row appears only when we hold the fact for both models. Anything the provider has not published is left out rather than guessed, so an empty row is missing data and never a zero.
Verdict
Which to pick
Both sit at the top of their families. GPT-5.5 is priced aggressively on input tokens; Fable 5 is the pick where tool-use reliability and long-horizon agentic work decide the outcome. Behind one key, the honest answer is: run your own eval, switching is a string.
Keep looking
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FAQ
Frequently asked questions
What is the difference between Claude Fable 5 and GPT-5.5?
GPT-5.5 is 2.0x cheaper on input. GPT-5.5 is 1.7x cheaper on output. GPT-5.5 holds 256K tokens against 200K. Both run on the same endpoint and the same key here, so trying each is a one-line change to the model id.
Which is cheaper, Claude Fable 5 or GPT-5.5?
GPT-5.5 is, on input tokens. Output usually dominates the bill on generative work, so check the output row above against your own ratio of prompt to completion before deciding.
Can I switch between Claude Fable 5 and GPT-5.5 without changing my code?
Yes. Both are OpenAI-compatible through one CompanyFabric key, so switching is the model string and nothing else — no second SDK, no second contract, one prepaid balance across both.
Do I have to choose?
No. Send companyfabric/auto and we route each request to the cheapest model that can serve it, which is how most people use both without deciding in advance.
One key. Every model. Exact prices.
Run Claude Fable 5 and GPT-5.5 on the same key and compare them on your own prompts. Free starter credits included, no subscription required.