Claude Fable 5 vs GPT-6 Astra
GPT-6 Astra is the lower-priced of the two on Router One at base-tier rates (GPT-6 Astra: request input ≤ 272,000 tokens) — about 75% less on a 1M-input + 1M-output mix. Both carry a 1.05M context window. Claude Fable 5 answers on /v1/chat/completions and /v1/messages (Claude Code); GPT-6 Astra on /v1/chat/completions and /v1/responses (Codex CLI). Claude Fable 5 is in no plan and bills the wallet; GPT-6 Astra counts against the Flagship models allowance on Max and Ultra.
Claude Fable 5 and GPT-6 Astra compared on current per-token rates, context window, and capabilities — both callable through one OpenAI-compatible endpoint with per-request cost traces.
Claude Fable 5 vs GPT-6 Astra: rates, context window, and capabilities
| Spec | Claude Fable 5 | GPT-6 Astra |
|---|---|---|
| Input / 1M tokens | $8.00 | $2.00 |
| Output / 1M tokens | $40.00 | $10.00 |
| Cached input / 1M tokens | $0.80 | $0.20 |
| Context window | 1.05M | 1.05M |
| Capabilities | Chat, Streaming, Tool calling, Vision | Chat, Streaming, Tool calling, Vision |
| Subscription plans | Not in any plan — wallet | Flagship models — Max, Ultra |
| Detail page | Claude Fable 5 | GPT-6 Astra |
GPT-6 Astra: request input ≤ 272,000 tokens: Input $2.00 / 1M tokens, Output $10.00 / 1M tokens, Cache write $2.50 / 1M tokens, Cached input $0.20 / 1M tokens; request input > 272,000 tokens: Input $4.00 / 1M tokens, Output $15.00 / 1M tokens, Cache write $5.00 / 1M tokens, Cached input $0.40 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold.
What does 1M tokens cost on Claude Fable 5 vs GPT-6 Astra?
Base-tier rates: For a workload of 1M input plus 1M output tokens at current rates: Claude Fable 5 comes to $48.00, GPT-6 Astra comes to $12.00 — GPT-6 Astra is about 75% cheaper on this mix. Real workloads skew heavily toward input tokens, so weigh the input rate by your own ratio; the cached-input row above is the posted catalog rate for that model.
Switch between Claude Fable 5 and GPT-6 Astra
The API key and base URL stay the same, but this is not a one-string switch for every request. Per OpenAI's GPT-6 guide (checked 2026-10-01), GPT-6 Astra takes tool calls only on the Responses API, does not accept the none reasoning effort (OpenAI suggests low) and takes no temperature, top_p or logprobs settings. Router One serves Claude Fable 5 on /v1/messages and /v1/chat/completions, not on /v1/responses. So tool-using code has to change path as well as model: Claude Code (/v1/messages) runs only the Claude side and Codex CLI (/v1/responses) only the GPT side. On a Max or Ultra plan the billing changes too: GPT-6 Astra counts against the Flagship models allowance, while Claude Fable 5, in no plan tier as of the 2026-10-01 plan response, bills the wallet per token.
curl https://api.router.one/v1/chat/completions \
-H "Authorization: Bearer sk-your-router-one-key" \
-H "Content-Type: application/json" \
-d '{"model": "anthropic/claude-fable-5", "messages": [{"role": "user", "content": "Hello"}]}'
# Same request, other model — change one string:
# "model": "openai/gpt-6-astra"FAQ
Is Claude Fable 5 cheaper than GPT-6 Astra?
Compared at base-tier rates (GPT-6 Astra: request input ≤ 272,000 tokens). Input: Claude Fable 5 $8.00 vs GPT-6 Astra $2.00 / 1M tokens; GPT-6 Astra has the lower rate. Output: Claude Fable 5 $40.00 vs GPT-6 Astra $10.00 / 1M tokens; GPT-6 Astra has the lower rate. Total cost depends on the workload's input, output and cache usage. GPT-6 Astra: request input ≤ 272,000 tokens: Input $2.00 / 1M tokens, Output $10.00 / 1M tokens, Cache write $2.50 / 1M tokens, Cached input $0.20 / 1M tokens; request input > 272,000 tokens: Input $4.00 / 1M tokens, Output $15.00 / 1M tokens, Cache write $5.00 / 1M tokens, Cached input $0.40 / 1M tokens. The total input tokens in each request select the tier; its rates apply to the whole request, not only tokens above the threshold. Rates change; the /models page is the live source of truth.
Is Claude Fable 5 or GPT-6 Astra included in a Router One subscription?
Claude Fable 5 is in no Router One plan, so every call bills the wallet per token. GPT-6 Astra counts against the Flagship models allowance on Max and Ultra: Max 150 and Ultra 450 requests per 30-day cycle, shared by every model in that tier. GPT-6 Astra requests above its long-context threshold count as more than one quota request. Requests beyond a plan's allowance bill the wallet per token.
Can I switch between Claude Fable 5 and GPT-6 Astra without changing code?
The API key and base URL stay the same, but this is not a one-string switch for every request. Per OpenAI's GPT-6 guide (checked 2026-10-01), GPT-6 Astra takes tool calls only on the Responses API, does not accept the none reasoning effort (OpenAI suggests low) and takes no temperature, top_p or logprobs settings. Router One serves Claude Fable 5 on /v1/messages and /v1/chat/completions, not on /v1/responses. So tool-using code has to change path as well as model: Claude Code (/v1/messages) runs only the Claude side and Codex CLI (/v1/responses) only the GPT side. On a Max or Ultra plan the billing changes too: GPT-6 Astra counts against the Flagship models allowance, while Claude Fable 5, in no plan tier as of the 2026-10-01 plan response, bills the wallet per token.
Where do these numbers come from?
Specs and prices on this page render from the live Router One catalog — the same data as the /models page — and refresh with it. Pricing methodology is documented on /pricing-methodology. Rates on this page were read from the live catalog on 2026-11-05 (UTC) and refresh within the hour.