From prompt to request cost
Estimated request cost equals input tokens multiplied by $10 per million, plus expected output multiplied by $50 per million. Cached input is separate only when the provider publishes a rate.
Claude context window calculator
Check whether a Claude workflow fits.
Estimate prompt size, include retrieval and conversation history, and leave deliberate space for the response.
Claude Fable 51,000,000token context window
$10 input / 1M $1 cached / 1M $50 output / 1M
Official · verified 2026-07-31View provider pricing ↗What this page helps you decide
- Treat system instructions, messages, documents, and tools as one budget.
- Reserve output before judging whether the request fits.
- Keep headroom for longer real-world inputs and tool results.
Prices are planning references, not a billing guarantee. Check the provider’s current pricing before launch.
Estimate a Claude Fable 5 request
1,000,000 context
0input tokens · local estimate
$0.0000estimated input cost
$0.0250reserved output cost
$0.0250estimated request total
0.05% of context reserved. Planning estimate based on characters ÷ 4; provider tokenizers and structured requests can differ.
Count the assembled request
System instructions, conversation history, retrieved documents, tool definitions, files, and response length all matter. Use the visible prompt for drafting, then validate the final payload with Anthropic.
Before you rely on the number
Claude Fable 5 calculator questions
Is this Claude Fable 5 token count exact?
No. It is a private plain-text planning estimate. Anthropic tokenization, chat formatting, tools, files, and images can change the real count.
Does the prompt leave my browser?
No. The calculator runs locally in your browser. Only the page itself and published registry data are loaded from PromptCostLab.
How should I verify production cost?
Check the linked Anthropic pricing page, then compare the estimate with token usage returned by the real API request.