Claude Fable 5 vs Claude Sonnet 5
Claude Fable 5 and Claude Sonnet 5 are both Anthropic Claude 5 models, but they target different buyer decisions. Fable 5 is Anthropic's most capable widely released Mythos-class model for demanding reasoning and long-horizon agentic work, with documented refusal/fallback behavior and $10/M input pricing. Sonnet 5 is the balanced Sonnet-tier route for day-to-day coding and workflow automation at lower token cost.
Pick Claude Fable 5 when the workload needs Anthropic's highest generally available capability tier and you can accept refusal/fallback behavior plus the $10/M input and $50/M output launch price once access is restored. Pick Claude Sonnet 5 for cost-sensitive production coding, higher throughput, and mainstream API adoption where Sonnet-tier capability is enough.
Decision scorecard
Local evidence first| Signal | Claude Fable 5 | Claude Sonnet 5 |
|---|---|---|
| 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 | $10/1M tokens |
| Provider routes | 8 tracked | 5 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 10.8 points.
- Claude Fable 5 has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Claude Fable 5 for Coding, RAG, and Agents.
- Claude Sonnet 5 holds a shared-benchmark lead on GDP.pdf, ahead by 51.8 points.
- Claude Sonnet 5 has the lower cheapest tracked output price at $10/1M tokens.
- Claude Sonnet 5 uniquely exposes Code execution in local model data.
- Local decision data tags Claude Sonnet 5 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 Sonnet 5
$4,100
Cheapest tracked route/tier: Anthropic
Estimated monthly gap: $16,400. 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 Sonnet 5 is $40/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Claude Sonnet 5 adds Code execution 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 $40/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Code execution before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-06-09 | 2026-06-30 |
| Context window | 1m | 1m |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | - | 2026-01 |
Pricing and availability
| Pricing attribute | Claude Fable 5 | Claude Sonnet 5 |
|---|---|---|
| Input price | $10/1M tokens | $2/1M tokens |
| Output price | $50/1M tokens | $10/1M tokens |
| Providers |
Capabilities
| Capability | Claude Fable 5 | Claude Sonnet 5 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Claude Fable 5 | Claude Sonnet 5 |
|---|---|---|
| SWE-bench Verified | 96.0 | 85.2 |
| SWE-bench Pro | 80.3 | 63.2 |
| OSWorld-Verified | 85.0 | 81.2 |
| GDP.pdf | 29.8 | 81.6 |
| CursorBench | 72.9 | 47.7 |
| CursorBench | 70.5 | 47.7 |
| CursorBench | 68.4 | 47.7 |
| CursorBench | 66.5 | 47.7 |
| CursorBench | 65.2 | 47.7 |
| CursorBench | 62.1 | 47.7 |
Deep dive
The tier split is the main decision frame. Fable 5 is positioned above Sonnet 5 for long-horizon agentic engineering, computer use, and hard reasoning, while Sonnet 5 is the practical balanced model for teams that do not need Fable 5's premium tier or safety-routing complexity.
Fable 5's refusal and fallback behavior is unique in this pair. Anthropic documents safety classifiers that may refuse or route certain requests to Claude Opus 4.8. Sonnet 5 should not inherit those specs automatically; treat Fable-specific integration behavior as a Fable-only concern.
Availability still matters. Fable 5 launched June 9, 2026, was suspended June 12, and Anthropic says it redeployed July 1, 2026. Verify live Fable 5 access on your provider before production; Sonnet 5 remains the safer default Claude route when you need confirmed availability today.
Do not collapse Fable 5 and Claude Mythos 5. Mythos 5 is a restricted-access Glasswing model with different availability and starred benchmark rows. This page compares two generally marketed Claude tiers, not Mythos access programs.
FAQ
When should I use Claude Fable 5 instead of Sonnet 5?
Use Fable 5 when you need Anthropic's highest generally available capability tier for long-horizon agentic work and can accept the higher $10/M input price plus refusal/fallback behavior once access is restored. Use Sonnet 5 for balanced coding and workflow automation at lower cost.
How does Fable 5 refusal handling affect integrations?
Fable 5 may refuse or fall back to Claude Opus 4.8 on certain requests because of safety classifiers. Sonnet 5 does not share that exact behavior profile, so do not assume Sonnet integrations will see the same routing pattern.
Which Claude model is best for long-horizon work?
Claude Fable 5 is Anthropic's most capable widely released model for demanding long-horizon agentic work in the current taxonomy, but verify live access before committing. Sonnet 5 is the better default when cost and availability matter more than maximum capability tier.
Is Claude Fable 5 available now?
Anthropic launched Fable 5 June 9, suspended access June 12, and says it redeployed July 1, 2026. Verify your Claude API or cloud partner route before production. Sonnet 5 remains the safer default when you need confirmed availability today.
Continue comparing
Last reviewed: 2026-07-26. Data sourced from public model cards and provider documentation.