Claude Fable 5 vs Gemini 3.1 Pro Preview
Claude Fable 5 (2026) and Gemini 3.1 Pro Preview (2026) are frontier reasoning models from Anthropic and Google DeepMind. Claude Fable 5 ships a 1m-token context window, while Gemini 3.1 Pro Preview ships a 1m-token context window. On SWE-bench Verified, Claude Fable 5 leads by 15.4 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 Gemini 3.1 Pro Preview when coding workflow support matters.
Decision scorecard
Local evidence first| Signal | Claude Fable 5 | Gemini 3.1 Pro Preview |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | multimodal apps, tool-calling agents, and long-context analysis |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 1m |
| Cheapest output | $50/1M tokens | $12/1M tokens |
| Provider routes | 4 tracked | 5 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 15.4 points.
- Claude Fable 5 uniquely exposes Reasoning in local model data.
- Local decision data tags Claude Fable 5 for Coding, RAG, and Agents.
- Gemini 3.1 Pro Preview has the lower cheapest tracked output price at $12/1M tokens.
- Gemini 3.1 Pro Preview has broader tracked provider coverage for fallback and procurement flexibility.
- Gemini 3.1 Pro Preview uniquely exposes Code execution in local model data.
- Local decision data tags Gemini 3.1 Pro Preview 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
Gemini 3.1 Pro Preview
$4,600
Cheapest tracked route/tier: Google AI Studio
Estimated monthly gap: $15,900. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on GCP Vertex AI; start route-level A/B tests there.
- Gemini 3.1 Pro Preview is $38/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning before moving production traffic.
- Gemini 3.1 Pro Preview adds Code execution in local capability data.
- Provider overlap exists on GCP Vertex AI; start route-level A/B tests there.
- Claude Fable 5 is $38/1M 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.
- Claude Fable 5 adds Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-06-09 | 2026-02-19 |
| Context window | 1m | 1m |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | - | 2025-01 |
Pricing and availability
| Pricing attribute | Claude Fable 5 | Gemini 3.1 Pro Preview |
|---|---|---|
| Input price | $10/1M tokens |
|
| Output price | $50/1M tokens |
|
| Providers |
Capabilities
| Capability | Claude Fable 5 | Gemini 3.1 Pro Preview |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| 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 | Gemini 3.1 Pro Preview |
|---|---|---|
| SWE-bench Verified | 96.0 | 80.6 |
| SWE-bench Pro | 80.3 | 54.2 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Claude Fable 5 at 96 and Gemini 3.1 Pro Preview at 80.6, with Claude Fable 5 ahead by 15.4 points; SWE-bench Pro has Claude Fable 5 at 80.3 and Gemini 3.1 Pro Preview at 54.2, with Claude Fable 5 ahead by 26.1 points. The largest visible gap is 26.1 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 reasoning mode: Claude Fable 5 and code execution: Gemini 3.1 Pro Preview. Both models share vision, multimodal input, function calling, and tool use, 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 Gemini 3.1 Pro Preview lists tiered pricing: 0-200,001t is $2/1M input and $12/1M output; 200,001t+ is $4/1M input and $18/1M output. A 70/30 input-output blend puts Gemini 3.1 Pro Preview lower by about $17 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 5, so concentration risk also matters.
Choose Claude Fable 5 when reasoning depth are central to the workload. Choose Gemini 3.1 Pro Preview when coding workflow support, lower cheapest-tier input-token cost, and broader provider choice 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 Gemini 3.1 Pro Preview?
Claude Fable 5 supports 1m tokens, while Gemini 3.1 Pro Preview 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 Gemini 3.1 Pro Preview?
Claude Fable 5 lists $10/1M input and $50/1M output tokens on the cheapest tracked provider. Gemini 3.1 Pro Preview lists tiered pricing: 0-200,001t is $2/1M input and $12/1M output; 200,001t+ is $4/1M input and $18/1M 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 Gemini 3.1 Pro Preview open source?
Claude Fable 5 is listed under Proprietary. Gemini 3.1 Pro Preview 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 Gemini 3.1 Pro Preview?
Both Claude Fable 5 and Gemini 3.1 Pro Preview expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Claude Fable 5 or Gemini 3.1 Pro Preview?
Both Claude Fable 5 and Gemini 3.1 Pro Preview expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Claude Fable 5 and Gemini 3.1 Pro Preview?
Claude Fable 5 is available on Anthropic, AWS Bedrock, GCP Vertex AI, and Microsoft Foundry. Gemini 3.1 Pro Preview is available on Google AI Studio, GCP Vertex AI, OpenRouter, Replicate API, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-11. Data sourced from public model cards and provider documentation.