Fable 5 in Claude Code: Day One Cost Analysis — $210 API-equivalent, $0 Paid

A developer on r/ClaudeAI switched their Claude Code default model to claude-fable-5 on launch day and tracked the entire day's usage using Claude Code's built-in session logs. The results: 742 Fable replies across 5 sessions, with an API-equivalent cost of $210.15 — but $0.00 actually paid thanks to the plan window ending June 22.

Methodology

Claude Code writes session logs as local JSONL files, including per-message token usage. The developer parsed every Fable message across all projects and priced them at published API rates:

• Input tokens: $10 per million
• Output tokens: $50 per million
• Cache reads: 0.1x base input rate ($1 per million)
• Cache writes: 1.25x base input rate ($12.50 per million)

Day One Totals

• 742 Fable replies across 5 sessions
• 77,885 input tokens / 938,211 output tokens
• 124.3 million cache read tokens, 3.0 million cache write tokens
• API-equivalent cost: $210.15
• Actual cost: $0.00 (included in paid plans until June 22)

The heavy output token count (938K vs 78K input) is typical for Claude Code's agentic loops — the model iterates, generates code, and revises. Cache reads dominate at 124.3M tokens, indicating effective prompt caching.

Practical Takeaway

If you're on a paid plan, Fable 5 is available at no extra cost until June 22. The API-equivalent pricing gives a sense of the resource consumption; actual plan costs are fixed. To replicate this measurement, parse the JSONL session logs under ~/.claude/sessions/.