Claude Fable 5.2 vs GPT-5.1-Codex
Claude Fable 5.2 leads GPT-5.1-Codex on coding, 87.8 to 15.3 on the Vibe Coding Index, and GPT-5.1-Codex costs 4.0x less per output token ($10.00 vs $40.00 per million). Updated November 14, 2026; 12 benchmarks have a result for both.
Claude Fable 5.2 or GPT-5.1-Codex: which to pick
Pick Claude Fable 5.2 for coding: it scores 87.8 on the Vibe Coding Index against 15.3 for GPT-5.1-Codex.
Pick GPT-5.1-Codex for output tokens 4.0x cheaper ($10.00 vs $40.00 per million).
- Shared results
- 12
- Claude Fable 5.2 only
- 56
- GPT-5.1-Codex only
- 13
- Like-for-like categories
- 5 of 9
Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
Claude Fable 5.2
Claude Fable 5.2 scores 87.8 against 15.3.
4 and 2 benchmarks behind the scores
Intelligence
AA Intelligence Index
No call
Only Claude Fable 5.2 has a AA Intelligence Index result, 64.6.
Directional only
Web design
Design Arena: websites
Claude Fable 5.2
Claude Fable 5.2 leads, 1351 against 1154.
Same board, both measured
General
Vals Index
No call
Only Claude Fable 5.2 has a Vals Index result, 71.3%.
Directional only
Long documents
Listed context window
Claude Fable 5.2
Claude Fable 5.2 takes 1M tokens against 400K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
GPT-5.1-Codex
Claude Fable 5.2 $0.028, GPT-5.1-Codex $0.0063 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only GPT-5.1-Codex has the number, $0.892.
Directional only
At a glance
- Coding index
- Claude Fable 5.2 87.8 from 4 benchmarks, GPT-5.1-Codex 15.3 from 2 benchmarks.
- Widest category
- Coding, 59.1 points apart on average over 4 shared benchmarks.
- Widest single gap
- Vibe Code Bench (Vals AI): Claude Fable 5.2 93.8% against GPT-5.1-Codex 13.1%, 80.7 points apart on a 0 to 100 scale.
- Output price
- Claude Fable 5.2 $40.00 against GPT-5.1-Codex $10.00 per million output tokens, 4.0x apart.
- Context window
- Claude Fable 5.2 takes 1M tokens, GPT-5.1-Codex 400K.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Claude Fable 5.2 | Bars | GPT-5.1-Codex | Ties |
|---|---|---|---|---|
| Coding | 4 | 0 | ||
| Agentic work | 2 | 0 | ||
| Reasoning | 1 | 0 | ||
| Web design | 4 | 0 | ||
| General | 1 | 0 | ||
| All shared boards | 12 | 0 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index40
| Benchmark | Claude Fable 5.2 | GPT-5.1-Codex | Leader |
|---|---|---|---|
| SWE-bench Verified | Not measured | 66.0% | Only GPT-5.1-Codex measured |
| LiveBench coding | 79.2% | Not measured | Only Claude Fable 5.2 measured |
| LMArena WebDev | 1838 | 1338 | Claude Fable 5.2 |
| LiveCodeBench (Vals AI) | Not measured | 85.5% | Only GPT-5.1-Codex measured |
| Terminal-Bench 4 (Vals AI) | 65.2% | Not measured | Only Claude Fable 5.2 measured |
| Vibe Code Bench (Vals AI) | 93.8% | 13.1% | Claude Fable 5.2 |
| ProgramBench (Vals AI) | 19.0% | Not measured | Only Claude Fable 5.2 measured |
| SWE-bench Multimodal (Vals AI) | 62.3% | Not measured | Only Claude Fable 5.2 measured |
| LiveCodeBench (Artificial Analysis run) | Not measured | 84.9% | Only GPT-5.1-Codex measured |
| SciCode | 67.7% | Not measured | Only Claude Fable 5.2 measured |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 34.8% | Only GPT-5.1-Codex measured |
| Terminal-Bench 4.0 (Artificial Analysis run) | 61.6% | Not measured | Only Claude Fable 5.2 measured |
| FrontierCode 2.0 | 49.1% | Not measured | Only Claude Fable 5.2 measured |
| Terminal-Bench | Not measured | 57.8% | Only GPT-5.1-Codex measured |
| FrontierSWE | 69.9% | Not measured | Only Claude Fable 5.2 measured |
| ALE-Bench | 2509.8 | 1244.9 | Claude Fable 5.2 |
| LMArena WebDev: React | 1915 | Not measured | Only Claude Fable 5.2 measured |
| LMArena WebDev: HTML | 1738 | 1346 | Claude Fable 5.2 |
| GameBench 2 | 99.1 | Not measured | Only Claude Fable 5.2 measured |
| Terminal-Bench 2.0 | Not measured | 57.8% | Only GPT-5.1-Codex measured |
| CursorBench 4.0 | 60.0% | Not measured | Only Claude Fable 5.2 measured |
| Neither model has a result on the other 31 boards here | |||
IntelligenceDirectional onlyPublic boards, shown as published, kept out of the index2 boards, none shared
| Benchmark | Claude Fable 5.2 | GPT-5.1-Codex | Leader |
|---|---|---|---|
| AA Intelligence Index | 64.6 | Not measured | Only Claude Fable 5.2 measured |
| Epoch Capabilities Index | 173.4 | Not measured | Only Claude Fable 5.2 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Fable 5.2 | GPT-5.1-Codex | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | Not measured | 994 | Only GPT-5.1-Codex measured |
| Design Arena: agents building full-stack apps | 1402 | 1086 | Claude Fable 5.2 |
| Design Arena: agents building mobile apps | 1325 | 1191 | Claude Fable 5.2 |
| Design Arena: spreadsheets | 1434 | Not measured | Only Claude Fable 5.2 measured |
| LiveBench research | 94.5% | Not measured | Only Claude Fable 5.2 measured |
| LiveBench browser | 86.9% | Not measured | Only Claude Fable 5.2 measured |
| LiveBench long agentic | 82.9% | Not measured | Only Claude Fable 5.2 measured |
| Tax Agent Bench (Vals AI) | 32.1% | Not measured | Only Claude Fable 5.2 measured |
| Legal Research Bench (Vals AI) | 46.1% | Not measured | Only Claude Fable 5.2 measured |
| Harvey's Legal Agent Benchmark (Vals AI) | 5.0% | Not measured | Only Claude Fable 5.2 measured |
| BioMysteryBench (Vals AI) | 83.7% | Not measured | Only Claude Fable 5.2 measured |
| Terminal-Bench-Science (Vals AI) | 55.7% | Not measured | Only Claude Fable 5.2 measured |
| Vals Science Index | 63.7% | Not measured | Only Claude Fable 5.2 measured |
| τ²-Bench Telecom | Not measured | 83.0% | Only GPT-5.1-Codex measured |
| APEX-Agents | 80.1% | Not measured | Only Claude Fable 5.2 measured |
| Remote Labor Index | 41.3% | Not measured | Only Claude Fable 5.2 measured |
| SpireClimb | 15.5% | Not measured | Only Claude Fable 5.2 measured |
| Neither model has a result on the other 27 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Fable 5.2 | GPT-5.1-Codex | Leader |
|---|---|---|---|
| LiveBench reasoning | 88.8% | Not measured | Only Claude Fable 5.2 measured |
| MysteryMechanism (Vals AI) | 51.8% | Not measured | Only Claude Fable 5.2 measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 86.0% | Only GPT-5.1-Codex measured |
| Humanity's Last Exam (Artificial Analysis run) | 74.3% | 25.7% | Claude Fable 5.2 |
| HLE-Diamond (Artificial Analysis run) | 80.2% | Not measured | Only Claude Fable 5.2 measured |
| CritPt v2, hard subset (Artificial Analysis run) | 76.5% | Not measured | Only Claude Fable 5.2 measured |
| GPQA Diamond (Epoch AI run) | 93.9% | Not measured | Only Claude Fable 5.2 measured |
| ARC-AGI | 98.5% | Not measured | Only Claude Fable 5.2 measured |
| ARC-AGI-2 | 93.8% | Not measured | Only Claude Fable 5.2 measured |
| SimpleBench | 94.9% | Not measured | Only Claude Fable 5.2 measured |
| Chess puzzles | 79.0% | Not measured | Only Claude Fable 5.2 measured |
| Mystery game puzzles | 90.0% | Not measured | Only Claude Fable 5.2 measured |
| EBR-bench | 90.5% | Not measured | Only Claude Fable 5.2 measured |
| Humanity's Last Exam (Scale run) | 72.4% | Not measured | Only Claude Fable 5.2 measured |
| GoBench | 2566 | Not measured | Only Claude Fable 5.2 measured |
| Neither model has a result on the other 11 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
| Benchmark | Claude Fable 5.2 | GPT-5.1-Codex | Leader |
|---|---|---|---|
| AIME 2025 (Artificial Analysis run) | Not measured | 95.7% | Only GPT-5.1-Codex measured |
| OTIS Mock AIME | 99.7% | Not measured | Only Claude Fable 5.2 measured |
| FrontierMath, tiers 1 to 3 | 95.1% | Not measured | Only Claude Fable 5.2 measured |
| FrontierMath, tier 4 | 100.0% | Not measured | Only Claude Fable 5.2 measured |
| ProofBench | 100.0% | Not measured | Only Claude Fable 5.2 measured |
| MathArena | 82.8% | Not measured | Only Claude Fable 5.2 measured |
| Neither model has a result on the other 8 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index5 boards, none shared
| Benchmark | Claude Fable 5.2 | GPT-5.1-Codex | Leader |
|---|---|---|---|
| MMLU Pro (Artificial Analysis run) | Not measured | 86.0% | Only GPT-5.1-Codex measured |
| AA-Omniscience | 66.8 | Not measured | Only Claude Fable 5.2 measured |
| SimpleQA Verified | 94.0% | Not measured | Only Claude Fable 5.2 measured |
| PRBench Finance | 47.1% | Not measured | Only Claude Fable 5.2 measured |
| PRBench Legal | 49.0% | Not measured | Only Claude Fable 5.2 measured |
| Neither model has a result on the other 16 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Claude Fable 5.2 | GPT-5.1-Codex | Leader |
|---|---|---|---|
| Design Arena: websites | 1351 | 1154 | Claude Fable 5.2 |
| Design Arena: UI components | 1371 | 1227 | Claude Fable 5.2 |
| Design Arena: game dev | 1396 | 1127 | Claude Fable 5.2 |
| Design Arena: data viz | Not measured | 1210 | Only GPT-5.1-Codex measured |
| Design Arena: 3D | 1517 | Not measured | Only Claude Fable 5.2 measured |
| Design Arena: all code categories | 1373 | 1142 | Claude Fable 5.2 |
| LiveBench design | 85.1% | Not measured | Only Claude Fable 5.2 measured |
| Neither model has a result on the other 2 boards here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Fable 5.2 | GPT-5.1-Codex | Leader |
|---|---|---|---|
| Vals Index | 71.3% | Not measured | Only Claude Fable 5.2 measured |
| LiveBench data analysis | 81.5% | Not measured | Only Claude Fable 5.2 measured |
| IFBench | Not measured | 70.0% | Only GPT-5.1-Codex measured |
| Long context reasoning (AA-LCR) | 83.3% | 69.3% | Claude Fable 5.2 |
| GDPval-AA | 1831 | Not measured | Only Claude Fable 5.2 measured |
| DTBench | 99.2% | Not measured | Only Claude Fable 5.2 measured |
| LMCA | 70.6% | Not measured | Only Claude Fable 5.2 measured |
| Furniture assembly | 90.0% | Not measured | Only Claude Fable 5.2 measured |
| Neither model has a result on the other 41 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Fable 5.2 | GPT-5.1-Codex | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
GPT-5.1-Codex costs less
Repository review
50K input + 3K output tokens
GPT-5.1-Codex costs less
Agent loop
200K input + 10K output tokens
GPT-5.1-Codex costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Anthropic Claude Fable 5.2 | OpenAI GPT-5.1-Codex |
|---|---|---|
| Maker | Anthropic | OpenAI |
| Weights | No public weights listed | No public weights listed |
| Released | November 9, 2026 | November 13, 2025 |
| Context window | 1M | 400K |
| Input $/Mtok | $8.00 | $1.25 |
| Output $/Mtok | $40.00 | $10.00 |
| Coding index | 87.8 | 15.3 |
| Independent measurements behind it | 4 | 2 |
| Cost per solved task | Not computable | $0.892 |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Fable 5.2 better than GPT-5.1-Codex for coding?
Pick Claude Fable 5.2 for coding: it scores 87.8 on the Vibe Coding Index against 15.3 for GPT-5.1-Codex. Pick GPT-5.1-Codex for output tokens 4.0x cheaper ($10.00 vs $40.00 per million).
Which is cheaper, Claude Fable 5.2 or GPT-5.1-Codex?
Claude Fable 5.2 costs $8.00 per million input tokens and $40.00 per million output tokens; GPT-5.1-Codex costs $1.25 and $10.00. Cost per solved task is known for GPT-5.1-Codex only.
Which has the bigger context window, Claude Fable 5.2 or GPT-5.1-Codex?
Claude Fable 5.2, with 1M tokens against 400K.
How many benchmarks is the Claude Fable 5.2 vs GPT-5.1-Codex comparison based on?
12 benchmarks have a result for both models as of November 14, 2026. Claude Fable 5.2's coding index rests on 4 independent benchmarks and GPT-5.1-Codex's on 2. Where only one model has a result, the page says so instead of naming a winner.