Anthropic: Claude Fable 5 wins on more metrics (5 of 9), but the right pick depends on what you optimize for — see the breakdown below.
| Metric | Anthropic: Claude Fable 5 | OpenAI: GPT-5.4 Nano |
|---|---|---|
| Intelligence Index | 59.9✓ | 38.2 |
| Coding Index | 62.0✓ | 43.9 |
| GPQA Diamond | 93%✓ | 82% |
| Design Arena Elo | 1417✓ | — |
| Speed (tokens/sec) | — | 53✓ |
| Latency | — | 607ms✓ |
| Input price /M | $10.00 | $0.200✓ |
| Output price /M | $50.00 | $1.25✓ |
| Context window | 1M✓ | 400K |
| Capabilities | ReasoningToolsJSONVision | ReasoningToolsJSONVision |