Claude Fable 5 vs GPT-5.5
Claude Fable 5 (2026) and GPT-5.5 (2026) are frontier-tier reasoning models from Anthropic and OpenAI. Claude Fable 5 ships a 1m-token context window, while GPT-5.5 ships a 1.05m-token context window. On SWE-bench Verified, Claude Fable 5 leads by 13.4 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Claude Fable 5 is safer overall; choose GPT-5.5 when coding workflow support matters.
Decision scorecard
Local evidence first| Signal | Claude Fable 5 | GPT-5.5 |
|---|---|---|
| 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 | 1.05m |
| Cheapest output | $50/1M tokens | $30/1M tokens |
| Provider routes | 4 tracked | 3 tracked |
| Shared benchmarks | SWE-bench Verified leader | 2 rows |
Decision tradeoffs
- Claude Fable 5 holds a shared-benchmark lead on SWE-bench Verified, ahead by 13.4 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.
- GPT-5.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.5 has the lower cheapest tracked output price at $30/1M tokens.
- GPT-5.5 uniquely exposes Code execution in local model data.
- Local decision data tags GPT-5.5 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
GPT-5.5
$11,500
Cheapest tracked route/tier: OpenAI API 0-272K input tokens
Estimated monthly gap: $9,000. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Claude Fable 5 and GPT-5.5; plan for SDK, billing, or endpoint changes.
- GPT-5.5 is $20/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- GPT-5.5 adds Code execution in local capability data.
- No overlapping tracked provider route is sourced for GPT-5.5 and Claude Fable 5; plan for SDK, billing, or endpoint changes.
- Claude Fable 5 is $20/1M 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 | 2026-04-23 |
| Context window | 1m | 1.05m |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | - | 2025-12 |
Pricing and availability
| Pricing attribute | Claude Fable 5 | GPT-5.5 |
|---|---|---|
| Input price | $10/1M tokens |
|
| Output price | $50/1M tokens |
|
| Providers |
Capabilities
| Capability | Claude Fable 5 | GPT-5.5 |
|---|---|---|
| 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 | GPT-5.5 |
|---|---|---|
| SWE-bench Verified | 96.0 | 82.6 |
| SWE-bench Pro | 80.3 | 58.6 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Claude Fable 5 at 96 and GPT-5.5 at 82.6, with Claude Fable 5 ahead by 13.4 points; SWE-bench Pro has Claude Fable 5 at 80.3 and GPT-5.5 at 58.6, with Claude Fable 5 ahead by 21.7 points. The largest visible gap is 21.7 points on SWE-bench Pro, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on code execution: GPT-5.5. Both models share vision, multimodal input, reasoning mode, and function calling, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Claude Fable 5 lists $10/1M input and $50/1M output tokens on the cheapest tracked provider, while GPT-5.5 lists tiered pricing: 0-272K input tokens is $5/1M input and $30/1M output; 0-272,000t is $5/1M input and $30/1M output; 272K+ input tokens is $8/1M input and $36/1M output; 272,000t+ is $10/1M input and $45/1M output. A 70/30 input-output blend puts GPT-5.5 lower by about $9.50 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 4 providers versus 3, so concentration risk also matters.
Choose Claude Fable 5 when vision-heavy evaluation and broader provider choice are central to the workload. Choose GPT-5.5 when coding workflow support, larger context windows, and lower cheapest-tier input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Claude Fable 5 or GPT-5.5?
GPT-5.5 supports 1.05m tokens, while Claude Fable 5 supports 1m tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Claude Fable 5 or GPT-5.5?
Claude Fable 5 lists $10/1M input and $50/1M output tokens on the cheapest tracked provider. GPT-5.5 lists tiered pricing: 0-272K input tokens is $5/1M input and $30/1M output; 0-272,000t is $5/1M input and $30/1M output; 272K+ input tokens is $8/1M input and $36/1M output; 272,000t+ is $10/1M input and $45/1M output. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. Provider discounts or batch pricing can still change the final bill.
Is Claude Fable 5 or GPT-5.5 open source?
Claude Fable 5 is listed under Proprietary. GPT-5.5 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Claude Fable 5 or GPT-5.5?
Both Claude Fable 5 and GPT-5.5 expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Claude Fable 5 or GPT-5.5?
Both Claude Fable 5 and GPT-5.5 expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Where can I run Claude Fable 5 and GPT-5.5?
Claude Fable 5 is available on Anthropic, AWS Bedrock, GCP Vertex AI, and Microsoft Foundry. GPT-5.5 is available on OpenAI API, OpenRouter, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-09. Data sourced from public model cards and provider documentation.