Model comparison
Claude Fable 5.1 vs GPT-5.1-Codex-mini
Claude Fable 5.1 has enough public results to be ranked (#2); GPT-5.1-Codex-mini does not yet, so treat this comparison as directional.
Last verified . 1 shared benchmarks.
Summary
- They share 1 benchmark with published results for both. Claude Fable 5.1 scores higher in 2 categories and GPT-5.1-Codex-mini in 0 categories; 2 gaps are clear of the uncertainty.
- The widest gap is in coding, where Claude Fable 5.1 leads 70.5 to 31.4.
- GPT-5.1-Codex-mini is cheaper at $0.25 / $2 per million input/output tokens, against $10 / $50 for Claude Fable 5.1.
- Claude Fable 5.1 accepts more context: 1M tokens versus 400K.
Side by side
| Claude Fable 5.1 | GPT-5.1-Codex-mini | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Noometry Index | 68.5 | 36.9 |
| Released | 2026-09-01 | 2025-11-12 |
| Weights | Proprietary | Proprietary |
| Context window | 1M | 400K |
| Max output | 128K | 128K |
| Input $ / M tokens | $10 | $0.25 |
| Output $ / M tokens | $50 | $2 |
| Results tracked | 50 | 2 |
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Category by category
Coding Claude Fable 5.1 leads
Claude Fable 5.1: 70.5 (#2), GPT-5.1-Codex-mini: 31.4
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena WebDev | 1753 | 1244 |
| FrontierCode | 50.9% | — |
| CursorBench | 51.8% | — |
| FrontierSWE | 56.3% | — |
| SciCode | 63.1% | — |
| WeirdML | 92.9% | — |
| LMArena Coding | 1523 | — |
| MirrorCode | 73.3% | — |
| ALE-Bench | 2,143 | — |
Agentic & Tool Use Claude Fable 5.1 leads
Claude Fable 5.1: 50.8 (#5), GPT-5.1-Codex-mini: 38.3
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| Terminal-Bench | — | 61.6% |
| APEX-Agents | 68.6% | — |
| Remote Labor Index | 17.9% | — |
| GDP.pdf | 29.6% | — |
| Vending-Bench 2 | 5,422 | — |
Reasoning Not comparable
Claude Fable 5.1: 76.7 (#5), GPT-5.1-Codex-mini: —
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| ARC-AGI-2 | 90% | — |
| NYT Connections (extended) | 90% | — |
| ARC-AGI-1 | 97.5% | — |
| CritPt | 31.1% | — |
| Chess Puzzles | 47% | — |
| EBR-Bench | 57.1% | — |
| LMArena Hard Prompts | 1526 | — |
| Mystery Game Puzzles | 58% | — |
| DTBench | 97.6% | — |
| LMCA | 65.5% | — |
| Epoch Capabilities Index | 165 | — |
Math Not comparable
Claude Fable 5.1: 89.5 (#3), GPT-5.1-Codex-mini: —
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| FrontierMath (Tiers 1-3) | 90.2% | — |
| FrontierMath Tier 4 | 87.8% | — |
| OTIS Mock AIME 2024-2025 | 100% | — |
| ProofBench | 100% | — |
| LMArena Math | 1519 | — |
| FrontierMath Erdős | 0% | — |
Knowledge Not comparable
Claude Fable 5.1: 69.3 (#5), GPT-5.1-Codex-mini: —
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| Humanity's Last Exam | 46.5% | — |
| SimpleQA Verified | 70.8% | — |
| LMArena Expert | 1528 | — |
Multimodal Not comparable
Claude Fable 5.1: 54.1 (#4), GPT-5.1-Codex-mini: —
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena Vision | 1319 | — |
| Blueprint-Bench 2 | 41.9% | — |
| Furniture Assembly | 70% | — |
| LMArena Document | 1513 | — |
Multilingual Not comparable
Claude Fable 5.1: 59.5 (#2), GPT-5.1-Codex-mini: —
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena Non-English | 1509 | — |
| LMArena Chinese | 1589 | — |
| LMArena French | 1532 | — |
| LMArena German | 1495 | — |
| LMArena Japanese | 1565 | — |
| LMArena Russian | 1525 | — |
| LMArena Spanish | 1503 | — |
Instruction Following Not comparable
Claude Fable 5.1: 79.3 (#6), GPT-5.1-Codex-mini: —
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena Instruction Following | 1515 | — |
Long Context Not comparable
Claude Fable 5.1: 46.8 (#19), GPT-5.1-Codex-mini: —
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena Longer Query | 1524 | — |
Writing & Preference Not comparable
Claude Fable 5.1: 79.3 (#1), GPT-5.1-Codex-mini: —
| Benchmark | Claude Fable 5.1 | GPT-5.1-Codex-mini |
|---|---|---|
| LMArena Text | 1511 | — |
| LMArena Creative Writing | 1507 | — |
| EQ-Bench Creative Writing | 2162 | — |
| LMArena Multi-Turn | 1492 | — |
Frequently asked questions
Is Claude Fable 5.1 better than GPT-5.1-Codex-mini?
Claude Fable 5.1 has enough public results to be ranked (#2); GPT-5.1-Codex-mini does not yet, so treat this comparison as directional.
Which is cheaper, Claude Fable 5.1 or GPT-5.1-Codex-mini?
GPT-5.1-Codex-mini is cheaper. It lists at $0.25 per million input tokens and $2 per million output tokens; Claude Fable 5.1 lists at $10 and $50.
Is Claude Fable 5.1 or GPT-5.1-Codex-mini better for coding?
Claude Fable 5.1 scores higher on coding benchmarks: 70.5 versus 31.4 in the Noometry coding category.
Which has the bigger context window?
Claude Fable 5.1 does, with 1M tokens against 400K.
How many benchmarks do Claude Fable 5.1 and GPT-5.1-Codex-mini share?
1 benchmark has published results for both models. Claude Fable 5.1 has 50 scored results on Noometry and GPT-5.1-Codex-mini has 2.