GPT-5.4 Pro vs GPT-5.6 Sol vs Claude Fable 5
Too close to call on our weighted score (GPT-5.6 Sol 66, Claude Fable 5 65, GPT-5.4 Pro 60). The right pick depends on what you value most.
OpenAIGPT-5.4 Pro
60/100- ECI159.1
- Price$30.00 / $180.00
- Context1.05M
- OpenAI
GPT-5.6 Sol
66/100- ECI161.8
- Price$4.00 / $20.00
- Context1.05M
AnthropicClaude Fable 5
65/100- ECI162.2
- Price$10.00 / $50.00
- Context1M
Too close to call
It is close. Our weighted score puts them within 2 points (GPT-5.6 Sol 66/100, Claude Fable 5 65/100, GPT-5.4 Pro 60/100), so choose by what matters most for your work: Claude Fable 5 for raw capability and GPT-5.6 Sol on price. 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 · GPT-5.4 Pro 159.1
- Lowest priceGPT-5.6 SolGPT-5.6 Sol $8.00 · Claude Fable 5 $20.00 · GPT-5.4 Pro $67.50 per 1M tokens (3:1 blend)
- Longest contextGPT-5.4 Pro and GPT-5.6 SolGPT-5.4 Pro 1,050,000 · GPT-5.6 Sol 1,050,000 · Claude Fable 5 1,000,000 tokens
- Widest inputsGPT-5.6 Sol and Claude Fable 5GPT-5.4 Pro: Text, Images · GPT-5.6 Sol: Text, Images, PDFs · Claude Fable 5: Text, Images, PDFs
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | GPT-5.4 Pro | GPT-5.6 Sol | Claude Fable 5 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 90 | 93 | 94 |
| Price | 25% | 0 | 7 | 0 |
| Inputs & features | 15% | 60 | 80 | 80 |
| Context window | 10% | 61 | 61 | 60 |
| Overall | 100% | 60/100 | 66/100 | 65/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.4 ProOpenAI | GPT-5.6 SolOpenAI | Claude Fable 5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 159.1 | 161.8 | 162.2 (best) |
| ECI rank | #11 of 148 | #8 of 148 | #7 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 94.6% (best) | 93.5% | 85.9% |
| FrontierMath Tiers 1–3Research-level mathematics | 82.5% | 89.1% (best) | 87.0% |
| OTIS Mock AIME 2024–2025Competition mathematics | — | 100% | 100% |
| SimpleQA VerifiedShort factual questions | 46.3% | 69.7% | 70.7% (best) |
| Price per million tokens | |||
| Input | $30.00 | $4.00 (best) | $10.00 |
| Output | $180.00 | $20.00 (best) | $50.00 |
| Cached input | — | $0.40 (best) | $1.00 |
| Blended (3:1) | $67.50 | $8.00 (best) | $20.00 |
| Long-context rate | Over 272K: $60.00 / $270.00 | Over 272K: $8.00 / $30.00 | Same rate |
| Price source | Official OpenAI API | Official OpenAI API | Official Anthropic API |
| Limits | |||
| Context window | 1,050,000 tokens (best) | 1,050,000 tokens (best) | 1,000,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens | 128,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | No | Yes | Yes |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yesmedium · high · xhigh | Yeslow · medium · high · xhigh · max | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | No | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | gpt-5.4-pro | gpt-5.6-sol | claude-fable-5 |
| API providers | 16 | 40 (best) | 38 |
| Released | Mar 5, 2026 | Jul 9, 2026 | Jun 9, 2026 |
| Knowledge cutoff | Aug 31, 2025 | Feb 16, 2026 | Jan 31, 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GPT-5.4 Pro$660.00
- GPT-5.6 Sol$80.00
- Claude Fable 5$200.00
Which should you choose?
Which is better: GPT-5.4 Pro, GPT-5.6 Sol or Claude Fable 5?
It is close. Our weighted score puts them within 2 points (GPT-5.6 Sol 66/100, Claude Fable 5 65/100, GPT-5.4 Pro 60/100), so choose by what matters most for your work: Claude Fable 5 for raw capability and GPT-5.6 Sol on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-5.4 Pro, GPT-5.6 Sol or Claude Fable 5?
GPT-5.6 Sol is cheaper at $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); GPT-5.4 Pro costs $30.00 input / $180.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $8.00 per million tokens for GPT-5.6 Sol versus $20.00 for Claude Fable 5 (2.5× as much) and $67.50 for GPT-5.4 Pro (8.4× 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 GPT-5.4 Pro 159.1 (#11 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 — GPT-5.4 Pro 94.6%, 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%, GPT-5.4 Pro 82.5%; SimpleQA Verified — Claude Fable 5 70.7%, GPT-5.6 Sol 69.7%, GPT-5.4 Pro 46.3%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-5.4 Pro, GPT-5.6 Sol and Claude Fable 5 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-5.4 Pro and GPT-5.6 Sol have the largest context windows (1,050,000 and 1,050,000 tokens), against 1,000,000 for Claude Fable 5. Maximum output per response: GPT-5.4 Pro up to 128,000, GPT-5.6 Sol up to 128,000, Claude Fable 5 up to 128,000 tokens.
Which can read images, PDFs, audio or video?
GPT-5.4 Pro accepts text and images; GPT-5.6 Sol accepts text, images and PDFs; Claude Fable 5 accepts text, images and PDFs. GPT-5.6 Sol handles the widest range of inputs.
Are any of these open source?
No. GPT-5.4 Pro, GPT-5.6 Sol and Claude Fable 5 are proprietary and only available through APIs and apps.
Which is newer?
GPT-5.6 Sol is the newest, released Jul 9, 2026. Claude Fable 5 came out Jun 9, 2026; GPT-5.4 Pro came out Mar 5, 2026. Knowledge cutoff: GPT-5.4 Pro Aug 31, 2025, GPT-5.6 Sol Feb 16, 2026, Claude Fable 5 Jan 31, 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.
