Claude Fable 5 vs GPT-5.3 Codex vs GPT-5.4 Pro
Too close to call on our weighted score (Claude Fable 5 65, GPT-5.3 Codex 64, GPT-5.4 Pro 60). The right pick depends on what you value most.
AnthropicClaude Fable 5
65/100- ECI162.2
- Price$10.00 / $50.00
- Context1M
OpenAIGPT-5.3 Codex
64/100- ECI156.8
- Price$1.75 / $14.00
- Context400K
- OpenAI
GPT-5.4 Pro
60/100- ECI159.1
- Price$30.00 / $180.00
- Context1.05M
Too close to call
It is close. Our weighted score puts them within a point (Claude Fable 5 65/100, GPT-5.3 Codex 64/100, GPT-5.4 Pro 60/100), so choose by what matters most for your work: Claude Fable 5 for raw capability, GPT-5.3 Codex on price and GPT-5.4 Pro 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-5.4 Pro 159.1 · GPT-5.3 Codex 156.8
- Lowest priceGPT-5.3 CodexGPT-5.3 Codex $4.81 · Claude Fable 5 $20.00 · GPT-5.4 Pro $67.50 per 1M tokens (3:1 blend)
- Longest contextGPT-5.4 ProGPT-5.4 Pro 1,050,000 · Claude Fable 5 1,000,000 · GPT-5.3 Codex 400,000 tokens
- Widest inputsClaude Fable 5 and GPT-5.3 CodexClaude Fable 5: Text, Images, PDFs · GPT-5.3 Codex: Text, Images, PDFs · GPT-5.4 Pro: Text, Images
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Claude Fable 5 | GPT-5.3 Codex | GPT-5.4 Pro |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 94 | 87 | 90 |
| Price | 25% | 0 | 18 | 0 |
| Inputs & features | 15% | 80 | 80 | 60 |
| Context window | 10% | 60 | 44 | 61 |
| Overall | 100% | 65/100 | 64/100 | 60/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Fable 5Anthropic | GPT-5.3 CodexOpenAI | GPT-5.4 ProOpenAI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 162.2 (best) | 156.8 | 159.1 |
| ECI rank | #7 of 148 (best) | #18 of 148 | #11 of 148 |
| GPQA DiamondGraduate-level science questions | 85.9% | — | 94.6% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 87.0% (best) | — | 82.5% |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% | — | — |
| SWE-bench VerifiedFixing real GitHub issues | — | 74.8% | — |
| SimpleQA VerifiedShort factual questions | 70.7% (best) | — | 46.3% |
| Price per million tokens | |||
| Input | $10.00 | $1.75 (best) | $30.00 |
| Output | $50.00 | $14.00 (best) | $180.00 |
| Cached input | $1.00 | $0.175 (best) | — |
| Blended (3:1) | $20.00 | $4.81 (best) | $67.50 |
| Long-context rate | Same rate | Same rate | Over 272K: $60.00 / $270.00 |
| Price source | Official Anthropic API | Official OpenAI API | Official OpenAI API |
| Limits | |||
| Context window | 1,000,000 tokens | 400,000 tokens | 1,050,000 tokens (best) |
| Max output | 128,000 tokens | 128,000 tokens | 128,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | No |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yeslow · medium · high · xhigh | Yesmedium · high · xhigh |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | No |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | claude-fable-5 | gpt-5.3-codex | gpt-5.4-pro |
| API providers | 38 (best) | 19 | 16 |
| Released | Jun 9, 2026 | Feb 5, 2026 | Mar 5, 2026 |
| Knowledge cutoff | Jan 31, 2026 | Aug 31, 2025 | Aug 31, 2025 |
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
- GPT-5.3 Codex$45.50
- GPT-5.4 Pro$660.00
Which should you choose?
Which is better: Claude Fable 5, GPT-5.3 Codex or GPT-5.4 Pro?
It is close. Our weighted score puts them within a point (Claude Fable 5 65/100, GPT-5.3 Codex 64/100, GPT-5.4 Pro 60/100), so choose by what matters most for your work: Claude Fable 5 for raw capability, GPT-5.3 Codex on price and GPT-5.4 Pro for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, Claude Fable 5, GPT-5.3 Codex or GPT-5.4 Pro?
GPT-5.3 Codex is cheaper at $1.75 input / $14.00 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 $4.81 per million tokens for GPT-5.3 Codex versus $20.00 for Claude Fable 5 (4.2× as much) and $67.50 for GPT-5.4 Pro (14× 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-5.4 Pro 159.1 (#11 of 148) and GPT-5.3 Codex 156.8 (#18 of 148). The confidence ranges of the top two overlap (159.6–166.1 vs 156.5–161.9), so treat the gap as small.
Which is better for coding?
There are no published SWE-bench Verified results for Claude Fable 5 and GPT-5.4 Pro 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 has the largest context window at 1,050,000 tokens, against 1,000,000 for Claude Fable 5 and 400,000 for GPT-5.3 Codex. Maximum output per response: Claude Fable 5 up to 128,000, GPT-5.3 Codex up to 128,000, GPT-5.4 Pro up to 128,000 tokens.
Which can read images, PDFs, audio or video?
Claude Fable 5 accepts text, images and PDFs; GPT-5.3 Codex accepts text, images and PDFs; GPT-5.4 Pro accepts text and images. Claude Fable 5 handles the widest range of inputs.
Are any of these open source?
No. Claude Fable 5, GPT-5.3 Codex and GPT-5.4 Pro are proprietary and only available through APIs and apps.
Which is newer?
Claude Fable 5 is the newest, released Jun 9, 2026. GPT-5.4 Pro came out Mar 5, 2026; GPT-5.3 Codex came out Feb 5, 2026. Knowledge cutoff: Claude Fable 5 Jan 31, 2026, GPT-5.3 Codex Aug 31, 2025, GPT-5.4 Pro Aug 31, 2025.
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.
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