Claude Fable 5.1 vs Inkling-Small: Specs & Benchmark Comparison
Claude Fable 5.1 is developed by Anthropic, while Inkling-Small comes from Thinking Machines Lab. Inkling-Small was released in July 2026, and Claude Fable 5.1 followed 2 months later in September 2026. Inkling-Small has a published size of about 276 billion parameters; Anthropic has not disclosed the parameter count of Claude Fable 5.1.
The two models share 2 published benchmarks. Claude Fable 5.1 leads on 2 of them. The widest gaps are on Humanity's Last Exam, where Claude Fable 5.1 scores 65.0% against 31.6%; GDPval-AA, where Claude Fable 5.1 scores 61.8% against 42.3%. Averaged across everything we track, Claude Fable 5.1 sits at 59.7% and Inkling-Small at 60.3%.
Inkling-Small is the cheaper API at $0.30 per million input tokens and $1.20 per million output tokens, roughly 33 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 256K for Inkling-Small. Claude Fable 5.1 accepts text and images as input, while Inkling-Small 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-Small |
|---|---|---|
| Company | Anthropic | Thinking Machines Lab |
| Release Date | September 1, 2026 | July 30, 2026 |
| Parameters | — | 276B |
| Multimodal | Yes | Yes |
| Context (input) | 1.0M | 256K |
| Context (output) | 128K | 256K |
| Input Price / 1M | $10.00 | $0.30 |
| Output Price / 1M | $50.00 | $1.20 |
| Average Score | 59.7% | 60.3% |
| Benchmarks | ||
| Humanity's Last Exam | 65.0% | 31.6% |
| GDPval-AA | 61.8% | 42.3% |
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-Small — 0.6.
Inkling-Small is 40.0x cheaper: input $0.30/1M vs $10.00/1M tokens.
Claude Fable 5.1 supports a larger context: 1M vs 256K tokens.
Claude Fable 5.1 is newer: released 9/1/2026 vs 7/30/2026.
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Frequently Asked Questions
Which is better for coding — Claude Fable 5.1 or Inkling-Small?
Which model is cheaper — Claude Fable 5.1 or Inkling-Small?
Which has a larger context window — Claude Fable 5.1 or Inkling-Small?
The Claude Fable 5.1 and Inkling-Small 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-Small page. See also the complete list of AI model comparisons.