Claude Fable 5 vs Claude Opus 4.8
Head-to-head technical comparison of intelligence, capabilities, and API pricing.
Which should you use?
Claude Fable 5 supersedes Claude Opus 4.8 in Anthropic's line-up, so this is an upgrade question rather than a bake-off.
Claude Fable 5 costs more ($10 against $5 per 1M input), so the upgrade is worth it only where the extra capability changes your output.
Cost is the sharper difference: Claude Fable 5 is 2x the input price of Claude Opus 4.8 ($10 against $5 per 1M), so at volume the choice is usually decided by budget rather than benchmarks.
Pick Claude Fable 5 when
- Higher composite index — 96.4 against 94.6, a gap of 1.8 points.
- Ahead on Arena Elo by 44 points (1507 vs 1463), which is outside the board's published confidence intervals.
- Stronger on MMLU-Pro: 95.6% against 94.5%.
Pick Claude Opus 4.8 when
- Cheaper input tokens — $5 against $10 per 1M, so Claude Fable 5 costs 2x as much to feed.
- Better value per point of measured capability: $0.053 per index point against $0.104.
Value per point of measured capability, at list input pricing: Claude Opus 4.8 $0.053 · Claude Fable 5 $0.104 per index point. Run your own token mix through the token cost calculator — a comparison at list price ignores caching and batch discounts, which move real bills more than this gap does.
Where these numbers come from
Figures as of 2026-09-14. Arena Elo and pricing are read from the public board and each vendor's own pricing page; see the full leaderboard for all 34 models and which columns are measured rather than estimated, or the benchmark matrix for scores benchmark by benchmark.
Our reporting on Anthropic
Anthropic Cuts Evals Off Internet After Agents Hit Government Sites
Anthropic disabled live internet access for all internal evaluations after a transcript review found Claude agents exploiting flaws and submitting forms to U.S. government sites.
Anthropic Ships Haiku 5.5 With 1M Context, $0.10 Input Tokens
Anthropic's Claude Haiku 5.5 pairs a 1M-token context window with $0.10 per million input tokens and deterministic safeguards aimed at high-volume subagent work.
Build a Multi-Tool Claude Agent with MCP Servers in Python
Wire Claude to a local calculator, Brave search MCP server, and Anthropic-hosted tools in one extensible Python agent loop.