Claude Fable 5.1 vs Inkling: Specs & Benchmark Comparison
Claude Fable 5.1 is developed by Anthropic, while Inkling comes from Thinking Machines Lab. Inkling was released in July 2026, and Claude Fable 5.1 followed 2 months later in September 2026. Inkling has a published size of about 975 billion parameters; Anthropic has not disclosed the parameter count of Claude Fable 5.1.
We have 7 benchmark results for Claude Fable 5.1 and 16 benchmark results for Inkling, but they overlap on a single test: GDPval-AA, where Claude Fable 5.1 scores 61.8% against 41.3%.
Inkling is the cheaper API at $0.95 per million input tokens and $4.05 per million output tokens, roughly 11 times cheaper than Claude Fable 5.1 at $10 and $50. Claude Fable 5.1 takes the larger context window at 1M tokens, compared with 524K for Inkling. Claude Fable 5.1 accepts text and images as input, while Inkling accepts text, images, and audio. On tooling, only Claude Fable 5.1 supports function calling and only Claude Fable 5.1 offers structured output.
| Characteristic | Claude Fable 5.1 | Inkling |
|---|---|---|
| Company | Anthropic | Thinking Machines Lab |
| Release Date | September 1, 2026 | July 21, 2026 |
| Parameters | — | 975B |
| Multimodal | Yes | Yes |
| Context (input) | 1.0M | 524K |
| Context (output) | 128K | 524K |
| Input Price / 1M | $10.00 | $0.95 |
| Output Price / 1M | $50.00 | $4.05 |
| Average Score | 59.7% | 61.8% |
| Benchmarks | ||
| GDPval-AA | 61.8% | 41.3% |
Visual Benchmark Comparison
Verdict
Claude Fable 5.1 leads in 2 out of 4 comparison categories.
Both models show comparable average scores: Claude Fable 5.1 — 0.6, Inkling — 0.6.
Inkling is 12.0x cheaper: input $0.95/1M vs $10.00/1M tokens.
Claude Fable 5.1 supports a larger context: 1M vs 524K tokens.
Claude Fable 5.1 is newer: released 9/1/2026 vs 7/21/2026.
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Frequently Asked Questions
Which is better for coding — Claude Fable 5.1 or Inkling?
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The Claude Fable 5.1 and Inkling comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the Claude Fable 5.1 or Inkling page. See also the complete list of AI model comparisons.