Claude Fable 5.1 vs Claude Opus 4.8
Select two models to compare their coding performance, pricing, and features.
Key Takeaways
| Metric | Claude Fable 5.1 | Claude Opus 4.8 |
|---|---|---|
| Coding Index | 120.65 | 107.83 |
| Coding tier | S+ | A+ |
| Input Price | $10/1M | $5/1M |
| Output Price | $50/1M | $25/1M |
| Context Window | 1M | 1M |
Coding Index
Coding Index · Reference baseline: 100
Integer index difference: 12.82
DeepSeek V4 Flash 0731 = 100. The index reflects two shared tests, not capability multiples or statistically established gaps.
Verdict
The models have different editorial tier assessments. The index is supplementary and cannot predict performance on every development task.
Capabilities & Use Cases Comparison
Claude Fable 5.1 Tier S+
- •Multi-file refactoring
- •Front-end development
- •Agentic coding
- •Long-running refactors and visual development
Claude Opus 4.8 Tier A+
- •Complex architecture
- •Multi-file refactoring
- •Code review
- •Claude Code
- •Best-in-class code reasoning and architecture design
- •Excels at complex multi-file refactoring
- •Superior at understanding large codebases
- •Strong at following nuanced instructions
Claude Fable 5.1
Benchmark evidence and ranking method · Claude Fable 5.1
Cross-checked
Terminal-Bench 4.0 · Claude Code · max: 57.88% · 95% CI ± 3.76%
Artificial Analysis · Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)
Test configuration: max
Terminal-Bench 2.1: 91.39% · SciCode: 63.08%
LiveBench · 2026-06-25 · claude-fable-5-1-max-effort
Coding: 86.38% · Agentic Coding: 66.06%
ModelRank assigns editorial tiers using public coding evidence, not automatic index thresholds or statistically proven classes. Price, speed, context size and sponsorship do not affect tiers.
DeepSeek V4 Flash 0731 = 100. The index reflects two shared tests, not capability multiples or statistically established gaps.
Results reflect particular model configurations. Agent harnesses, reasoning effort, tools, budgets and tasks may differ. Close indices do not establish superiority. B describes a relative position in this selected group, not an inability to code.
Data checked: 2026-09-10. Snapshot date is the retrieval date, not necessarily the evaluation date.
Claude Opus 4.8
Benchmark evidence and ranking method · Claude Opus 4.8
Cross-checked
Terminal-Bench 4.0 · Claude Code · max: 23.64% · 95% CI ± 3.56%
Artificial Analysis · Claude Opus 4.8 (Adaptive Reasoning, Max Effort)
Test configuration: max
Terminal-Bench 2.1: 84.64% · SciCode: 54.40%
LiveBench · 2026-06-25 · claude-opus-4-8-max-effort
Coding: 81.83% · Agentic Coding: 50.50%
ModelRank assigns editorial tiers using public coding evidence, not automatic index thresholds or statistically proven classes. Price, speed, context size and sponsorship do not affect tiers.
DeepSeek V4 Flash 0731 = 100. The index reflects two shared tests, not capability multiples or statistically established gaps.
Results reflect particular model configurations. Agent harnesses, reasoning effort, tools, budgets and tasks may differ. Close indices do not establish superiority. B describes a relative position in this selected group, not an inability to code.
Data checked: 2026-09-10. Snapshot date is the retrieval date, not necessarily the evaluation date.
Results reflect particular model configurations. Agent harnesses, reasoning effort, tools, budgets and tasks may differ. Close indices do not establish superiority. B describes a relative position in this selected group, not an inability to code.
API cost estimate
1M input + 200K output (USD):
Claude Fable 5.1: $20.0000
Claude Opus 4.8: $10.0000
Estimates use the displayed channel and time band; DeepSeek uses peak rates. Cache discounts, tool fees, long-context price tiers and uncounted additional tokens are excluded.
Frequently Asked Questions
Which model is better for coding: Claude Fable 5.1 or Claude Opus 4.8?
Claude Fable 5.1 has a higher reference index on the selected shared benchmark configuration than Claude Opus 4.8 (120.65 vs 107.83, a 12.82-point difference). This does not by itself establish general coding superiority. Editorial tiers: Claude Fable 5.1 = S+; Claude Opus 4.8 = A+. Tiers are separate editorial assessments and do not establish a reliable order within a tier.
How do Claude Fable 5.1 and Claude Opus 4.8 compare in API pricing and costs?
Claude Fable 5.1: $10/1M input, $50/1M output (OpenRouter quote); Claude Opus 4.8: $5/1M input, $25/1M output (OpenRouter quote). 1M input + 200K output (USD): $20.0000 vs $10.0000.
What are the context window sizes of Claude Fable 5.1 and Claude Opus 4.8?
Claude Fable 5.1 provides a 1,000,000 token context window, while Claude Opus 4.8 provides 1,000,000 tokens.