Claude Fable 5 vs Claude Opus 4.8
Claude Fable 5 and Claude Opus 4.8 are Anthropic's most important in-family comparison for teams deciding whether to move from the prior Opus generation to the Mythos-class Fable route. Anthropic says Fable 5's capabilities exceed any model it had previously made generally available, but Fable 5 also includes safeguards that can route some requests differently than Opus 4.8.
Pick Claude Fable 5 when you need Anthropic's most capable widely released Mythos-class route and can accept documented refusal and fallback behavior after verifying live access. Keep Claude Opus 4.8 when you need the prior Opus behavior profile, fallback predictability, or a route that may still be easier to reason about for some regulated workflows. Treat the June 9 launch, June 12 suspension, and July 1 redeploy timeline as part of the product decision, not a footnote.
Decision scorecard
Local evidence first| Signal | Claude Fable 5 | Claude Opus 4.8 |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 1m |
| Cheapest output | $50/1M tokens | $25/1M tokens |
| Provider routes | 8 tracked | 6 tracked |
| Shared benchmarks | SWE-bench Verified leader | 10 shared |
Decision tradeoffs
- Claude Fable 5 holds a shared-benchmark lead on SWE-bench Verified, ahead by 7.4 points.
- Claude Fable 5 has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags Claude Fable 5 for Coding, RAG, and Agents.
- Claude Opus 4.8 has the lower cheapest tracked output price at $25/1M tokens.
- Claude Opus 4.8 uniquely exposes Code execution, Computer use, and Parallel agents in local model data.
- Local decision data tags Claude Opus 4.8 for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Fable 5
$20,500
Cheapest tracked route/tier: Anthropic
Claude Opus 4.8
$10,250
Cheapest tracked route/tier: Anthropic
Estimated monthly gap: $10,250. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Anthropic, AWS Bedrock, and GCP Vertex AI; start route-level A/B tests there.
- Claude Opus 4.8 is $25/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Claude Opus 4.8 adds Code execution, Computer use, and Parallel agents in local capability data.
- Provider overlap exists on Anthropic, AWS Bedrock, and GCP Vertex AI; start route-level A/B tests there.
- Claude Fable 5 is $25/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Code execution, Computer use, and Parallel agents before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-06-09 | 2026-05-28 |
| Context window | 1m | 1m |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Not released |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | - | 2026-01 |
Pricing and availability
| Pricing attribute | Claude Fable 5 | Claude Opus 4.8 |
|---|---|---|
| Input price | $10/1M tokens | $5/1M tokens |
| Output price | $50/1M tokens | $25/1M tokens |
| Providers |
Capabilities
| Capability | Claude Fable 5 | Claude Opus 4.8 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
| IDE integration | No | No |
| Computer use | No | Yes |
| Parallel agents | No | Yes |
Benchmarks
| Benchmark | Claude Fable 5 | Claude Opus 4.8 |
|---|---|---|
| SWE-bench Verified | 96.0 | 88.6 |
| SWE-bench Pro | 80.3 | 69.2 |
| OSWorld-Verified | 85.0 | 83.4 |
| GDPval-AA | 1932.0 | 1890.0 |
| CursorBench | 72.9 | 53.1 |
| CursorBench | 70.5 | 53.1 |
| CursorBench | 68.4 | 53.1 |
| CursorBench | 66.5 | 53.1 |
| CursorBench | 65.2 | 53.1 |
| CursorBench | 62.1 | 53.1 |
Continue comparing
Popular comparisons for Claude Opus 4.8
Last reviewed: 2026-07-26. Data sourced from public model cards and provider documentation.