Claude Fable 5 vs Grok 4.6 vs GPT-5.6 Sol
Too close to call on our weighted score (GPT-5.6 Sol 66, Grok 4.6 65, Claude Fable 5 65). The right pick depends on what you value most.
AnthropicClaude Fable 5
65/100- ECI162.2
- Price$10.00 / $50.00
- Context1M
xAIGrok 4.6
65/100- ECI156.6
- Price$2.00 / $6.00
- Context500K
OpenAIGPT-5.6 Sol
66/100- ECI161.8
- Price$4.00 / $20.00
- Context1.05M
Too close to call
It is close. Our weighted score puts them within 1 points (GPT-5.6 Sol 66/100, Grok 4.6 65/100, Claude Fable 5 65/100), so choose by what matters most for your work: Claude Fable 5 for raw capability, Grok 4.6 on price and GPT-5.6 Sol for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityClaude Fable 5Capabilities Index (ECI): Claude Fable 5 162.2 · GPT-5.6 Sol 161.8 · Grok 4.6 156.6
- Lowest priceGrok 4.6Grok 4.6 $3.00 · GPT-5.6 Sol $8.00 · Claude Fable 5 $20.00 per 1M tokens (3:1 blend)
- Longest contextGPT-5.6 SolGPT-5.6 Sol 1,050,000 · Claude Fable 5 1,000,000 · Grok 4.6 500,000 tokens
- Widest inputsClaude Fable 5 and GPT-5.6 SolClaude Fable 5: Text, Images, PDFs · Grok 4.6: Text, Images · GPT-5.6 Sol: Text, Images, PDFs
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Claude Fable 5 | Grok 4.6 | GPT-5.6 Sol |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 94 | 86 | 93 |
| Price | 25% | 0 | 27 | 7 |
| Inputs & features | 15% | 80 | 70 | 80 |
| Context window | 10% | 60 | 48 | 61 |
| Overall | 100% | 65/100 | 65/100 | 66/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Fable 5Anthropic | Grok 4.6xAI | GPT-5.6 SolOpenAI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 162.2 (best) | 156.6 | 161.8 |
| ECI rank | #7 of 148 (best) | #19 of 148 | #8 of 148 |
| GPQA DiamondGraduate-level science questions | 85.9% | 94.0% (best) | 93.5% |
| FrontierMath Tiers 1–3Research-level mathematics | 87.0% | 66.0% | 89.1% (best) |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% (best) | 99.2% | 100% (best) |
| SimpleQA VerifiedShort factual questions | 70.7% (best) | 49.3% | 69.7% |
| Price per million tokens | |||
| Input | $10.00 | $2.00 (best) | $4.00 |
| Output | $50.00 | $6.00 (best) | $20.00 |
| Cached input | $1.00 | $0.50 | $0.40 (best) |
| Blended (3:1) | $20.00 | $3.00 (best) | $8.00 |
| Long-context rate | Same rate | Over 200K: $4.00 / $12.00 | Over 272K: $8.00 / $30.00 |
| Price source | Official Anthropic API | Official xAI API | Official OpenAI API |
| Limits | |||
| Context window | 1,000,000 tokens | 500,000 tokens | 1,050,000 tokens (best) |
| Max output | 128,000 tokens | 500,000 tokens (best) | 128,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | No | Yes |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yeslow · medium · high · xhigh | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | claude-fable-5 | grok-4.6 | gpt-5.6-sol |
| API providers | 38 | 29 | 40 (best) |
| Released | Jun 9, 2026 | Aug 12, 2026 | Jul 9, 2026 |
| Knowledge cutoff | Jan 31, 2026 | Feb 1, 2026 | Feb 16, 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Claude Fable 5$200.00
- Grok 4.6$32.00
- GPT-5.6 Sol$80.00
Which should you choose?
Which is better: Claude Fable 5, Grok 4.6 or GPT-5.6 Sol?
It is close. Our weighted score puts them within 1 points (GPT-5.6 Sol 66/100, Grok 4.6 65/100, Claude Fable 5 65/100), so choose by what matters most for your work: Claude Fable 5 for raw capability, Grok 4.6 on price and GPT-5.6 Sol for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Claude Fable 5, Grok 4.6 or GPT-5.6 Sol?
Grok 4.6 is cheaper at $2.00 input / $6.00 output per million tokens (official xAI API price). GPT-5.6 Sol costs $4.00 input / $20.00 output per million tokens (official OpenAI API price); Claude Fable 5 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 $3.00 per million tokens for Grok 4.6 versus $8.00 for GPT-5.6 Sol (2.7× as much) and $20.00 for Claude Fable 5 (6.7× as much).
Which scores higher on benchmarks?
Claude Fable 5 scores higher on the Capabilities Index (ECI): Claude Fable 5 162.2 (#7 of 148), GPT-5.6 Sol 161.8 (#8 of 148) and Grok 4.6 156.6 (#19 of 148). The confidence ranges of the top two overlap (159.6–166.1 vs 159.3–165.3), so treat the gap as small. On individual benchmarks: GPQA Diamond — Grok 4.6 94.0%, GPT-5.6 Sol 93.5%, Claude Fable 5 85.9%; FrontierMath Tiers 1–3 — GPT-5.6 Sol 89.1%, Claude Fable 5 87.0%, Grok 4.6 66.0%; OTIS Mock AIME 2024–2025 — Claude Fable 5 100%, GPT-5.6 Sol 100%, Grok 4.6 99.2%; SimpleQA Verified — Claude Fable 5 70.7%, GPT-5.6 Sol 69.7%, Grok 4.6 49.3%.
Which is better for coding?
There are no published SWE-bench Verified results for Claude Fable 5, Grok 4.6 and GPT-5.6 Sol yet, so there is no like-for-like coding score. On overall capability, Claude Fable 5 leads, which tends to carry over to coding, but test on your own codebase. All three support tool calling for agent workflows.
Which has the bigger context window?
GPT-5.6 Sol has the largest context window at 1,050,000 tokens, against 1,000,000 for Claude Fable 5 and 500,000 for Grok 4.6. Maximum output per response: Claude Fable 5 up to 128,000, Grok 4.6 up to 500,000, GPT-5.6 Sol up to 128,000 tokens.
Which can read images, PDFs, audio or video?
Claude Fable 5 accepts text, images and PDFs; Grok 4.6 accepts text and images; GPT-5.6 Sol accepts text, images and PDFs. Claude Fable 5 handles the widest range of inputs.
Are any of these open source?
No. Claude Fable 5, Grok 4.6 and GPT-5.6 Sol are proprietary and only available through APIs and apps.
Which is newer?
Grok 4.6 is the newest, released Aug 12, 2026. GPT-5.6 Sol came out Jul 9, 2026; Claude Fable 5 came out Jun 9, 2026. Knowledge cutoff: Claude Fable 5 Jan 31, 2026, Grok 4.6 Feb 1, 2026, GPT-5.6 Sol Feb 16, 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 Oct 4, 2026.
