Inkling Small vs Claude Fable 5.1
Too close to call on our weighted score (Inkling Small 68, Claude Fable 5.1 66). The right pick depends on what you value most.
Thinking MachinesInkling Small
68/100- ECI150.5
- Price$0.58 / $1.44
- Context1.05M
AnthropicClaude Fable 5.1
66/100- ECI166.4
- Price$10.00 / $50.00
- Context1M
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Make it a three-way comparison.
Too close to call
It is close. Our weighted score puts them within 2 points (Inkling Small 68/100, Claude Fable 5.1 66/100), so choose by what matters most for your work: Claude Fable 5.1 for raw capability, Inkling Small on price and Inkling Small for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityClaude Fable 5.1Capabilities Index (ECI): Claude Fable 5.1 166.4 · Inkling Small 150.5
- Lowest priceInkling SmallInkling Small $0.795 · Claude Fable 5.1 $20.00 per 1M tokens (3:1 blend)
- Longest contextInkling SmallInkling Small 1,048,576 · Claude Fable 5.1 1,000,000 tokens
- Widest inputsSame inputsInkling Small: Text, Images, Audio · Claude Fable 5.1: Text, Images, PDFs
- Self-hostingInkling SmallPublishes downloadable weights (Apache-2.0)
| Measure | Weight | Inkling Small | Claude Fable 5.1 |
|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 77 | 97 |
| Price | 25% | 52 | 0 |
| Inputs & features | 15% | 70 | 80 |
| Context window | 10% | 61 | 60 |
| Overall | 100% | 68/100 | 66/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Inkling SmallThinking Machines | Claude Fable 5.1Anthropic |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | 150.5 | 166.4 (best) |
| ECI rank | #58 of 165 | #6 of 165 (best) |
| GPQA DiamondGraduate-level science questions | 88.5% | — |
| FrontierMath Tiers 1–3Research-level mathematics | 46.3% | 90.2% (best) |
| OTIS Mock AIME 2024–2025Competition mathematics | 90.0% | 100% (best) |
| SimpleQA VerifiedShort factual questions | 19.1% | 70.8% (best) |
| Price per million tokens | ||
| Input | $0.58 (best) | $10.00 |
| Output | $1.44 (best) | $50.00 |
| Cached input | $0.116 (best) | $0.25 |
| Blended (3:1) | $0.795 (best) | $20.00 |
| Long-context rate | Same rate | Same rate |
| Price source | Official Thinking Machines API | Official Anthropic API |
| Limits | ||
| Context window | 1,048,576 tokens (best) | 1,000,000 tokens |
| Max output | 1,048,576 tokens (best) | 128,000 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | Yes | Yes |
| PDFs | No | Yes |
| Audio | Yes | No |
| Video | No | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes |
| Structured output | No | Yes |
| Availability | ||
| Weights | OpenApache-2.0 | Proprietary |
| API model ID | thinkingmachines/Inkling-Small | claude-fable-5-1 |
| API providers | 12 | 37 (best) |
| Released | Jul 30, 2026 | Sep 1, 2026 |
| Knowledge cutoff | — | Jun 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Inkling Small$8.68
- Claude Fable 5.1$200.00
Which should you choose?
Which is better: Inkling Small or Claude Fable 5.1?
It is close. Our weighted score puts them within 2 points (Inkling Small 68/100, Claude Fable 5.1 66/100), so choose by what matters most for your work: Claude Fable 5.1 for raw capability, Inkling Small on price and Inkling Small for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Inkling Small or Claude Fable 5.1?
Inkling Small is cheaper at $0.58 input / $1.44 output per million tokens (official Thinking Machines API price). Claude Fable 5.1 costs $10.00 input / $50.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $0.795 per million tokens for Inkling Small versus $20.00 for Claude Fable 5.1 (25× as much).
Which scores higher on benchmarks?
Claude Fable 5.1 scores higher on the Capabilities Index (ECI): Claude Fable 5.1 166.4 (#6 of 165) and Inkling Small 150.5 (#58 of 165). Their confidence ranges do not overlap (163.6–170.8 vs 147.7–152.4), so the gap is a real one. On individual benchmarks: FrontierMath Tiers 1–3 — Claude Fable 5.1 90.2%, Inkling Small 46.3%; OTIS Mock AIME 2024–2025 — Claude Fable 5.1 100%, Inkling Small 90.0%; SimpleQA Verified — Claude Fable 5.1 70.8%, Inkling Small 19.1%.
Which is better for coding?
There are no published SWE-bench Verified results for Inkling Small and Claude Fable 5.1 yet, so there is no like-for-like coding score. On overall capability, Claude Fable 5.1 leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.
Which has the bigger context window?
Inkling Small has the largest context window at 1,048,576 tokens, against 1,000,000 for Claude Fable 5.1. Maximum output per response: Inkling Small up to 1,048,576, Claude Fable 5.1 up to 128,000 tokens.
Which can read images, PDFs, audio or video?
Inkling Small accepts text, images and audio; Claude Fable 5.1 accepts text, images and PDFs. They handle the same number of input types.
Are any of these open source?
Inkling Small publishes its weights (Apache-2.0) and can be self-hosted; Claude Fable 5.1 is proprietary.
Which is newer?
Claude Fable 5.1 is the newest, released Sep 1, 2026. Inkling Small came out Jul 30, 2026. Knowledge cutoff: Claude Fable 5.1 Jun 2026.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Nov 2, 2026.
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