GPT-5.4 Pro vs GPT-5.5 Pro vs Claude Fable 5
Too close to call on our weighted score (GPT-5.5 Pro 65, 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-5.5 Pro
65/100- ECI162.4
- Price$30.00 / $180.00
- 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 a point (GPT-5.5 Pro 65/100, Claude Fable 5 65/100, GPT-5.4 Pro 60/100), so choose by what matters most for your work: GPT-5.5 Pro for raw capability and Claude Fable 5 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-5.5 ProCapabilities Index (ECI): GPT-5.5 Pro 162.4 · Claude Fable 5 162.2 · GPT-5.4 Pro 159.1
- Lowest priceClaude Fable 5Claude Fable 5 $20.00 · GPT-5.4 Pro $67.50 · GPT-5.5 Pro $67.50 per 1M tokens (3:1 blend)
- Longest contextGPT-5.4 Pro and GPT-5.5 ProGPT-5.4 Pro 1,050,000 · GPT-5.5 Pro 1,050,000 · Claude Fable 5 1,000,000 tokens
- Widest inputsGPT-5.5 Pro and Claude Fable 5GPT-5.4 Pro: Text, Images · GPT-5.5 Pro: 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-5.5 Pro | Claude Fable 5 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 90 | 94 | 94 |
| Price | 25% | 0 | 0 | 0 |
| Inputs & features | 15% | 60 | 80 | 80 |
| Context window | 10% | 61 | 61 | 60 |
| Overall | 100% | 60/100 | 65/100 | 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-5.5 ProOpenAI | Claude Fable 5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 159.1 | 162.4 (best) | 162.2 |
| ECI rank | #11 of 148 | #6 of 148 (best) | #7 of 148 |
| GPQA DiamondGraduate-level science questions | 94.6% (best) | 93.9% | 85.9% |
| FrontierMath Tiers 1–3Research-level mathematics | 82.5% | 87.7% (best) | 87.0% |
| OTIS Mock AIME 2024–2025Competition mathematics | — | 100% | 100% |
| SimpleQA VerifiedShort factual questions | 46.3% | — | 70.7% (best) |
| Price per million tokens | |||
| Input | $30.00 | $30.00 | $10.00 (best) |
| Output | $180.00 | $180.00 | $50.00 (best) |
| Cached input | — | — | $1.00 |
| Blended (3:1) | $67.50 | $67.50 | $20.00 (best) |
| Long-context rate | Over 272K: $60.00 / $270.00 | Over 272K: $60.00 / $270.00 | 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 | Yesmedium · high · xhigh | 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-5.5-pro | claude-fable-5 |
| API providers | 16 | 19 | 38 (best) |
| Released | Mar 5, 2026 | Apr 23, 2026 | Jun 9, 2026 |
| Knowledge cutoff | Aug 31, 2025 | Dec 1, 2025 | 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-5.5 Pro$660.00
- Claude Fable 5$200.00
Which should you choose?
Which is better: GPT-5.4 Pro, GPT-5.5 Pro or Claude Fable 5?
It is close. Our weighted score puts them within a point (GPT-5.5 Pro 65/100, Claude Fable 5 65/100, GPT-5.4 Pro 60/100), so choose by what matters most for your work: GPT-5.5 Pro for raw capability and Claude Fable 5 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-5.4 Pro, GPT-5.5 Pro or Claude Fable 5?
Claude Fable 5 is cheaper at $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); GPT-5.5 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 $20.00 per million tokens for Claude Fable 5 versus $67.50 for GPT-5.4 Pro (3.4× as much) and $67.50 for GPT-5.5 Pro (3.4× as much).
Which scores higher on benchmarks?
GPT-5.5 Pro scores higher on the Capabilities Index (ECI): GPT-5.5 Pro 162.4 (#6 of 148), Claude Fable 5 162.2 (#7 of 148) and GPT-5.4 Pro 159.1 (#11 of 148). The confidence ranges of the top two overlap (159.0–166.0 vs 159.6–166.1), so treat the gap as small. On individual benchmarks: GPQA Diamond — GPT-5.4 Pro 94.6%, GPT-5.5 Pro 93.9%, Claude Fable 5 85.9%; FrontierMath Tiers 1–3 — GPT-5.5 Pro 87.7%, Claude Fable 5 87.0%, GPT-5.4 Pro 82.5%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-5.4 Pro, GPT-5.5 Pro and Claude Fable 5 yet, so there is no like-for-like coding score. On overall capability, GPT-5.5 Pro 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-5.5 Pro 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-5.5 Pro 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-5.5 Pro accepts text, images and PDFs; Claude Fable 5 accepts text, images and PDFs. GPT-5.5 Pro handles the widest range of inputs.
Are any of these open source?
No. GPT-5.4 Pro, GPT-5.5 Pro and Claude Fable 5 are proprietary and only available through APIs and apps.
Which is newer?
Claude Fable 5 is the newest, released Jun 9, 2026. GPT-5.5 Pro came out Apr 23, 2026; GPT-5.4 Pro came out Mar 5, 2026. Knowledge cutoff: GPT-5.4 Pro Aug 31, 2025, GPT-5.5 Pro Dec 1, 2025, 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.
