Claude Fable 5.1 vs Grok 4.5
Full profiles: Claude Fable 5.1 (Anthropic) and Grok 4.5 (SpaceXAI): every benchmark, price and rank.
Updated · Data from 12 sources
As of 26 Oct 2026, Claude Fable 5.1 (max) leads on quality (70.5 vs 60.0 on the BenchLeader Index), but Grok 4.5 costs 6.7× less, so it is the better buy unless you need the extra quality. Claude Fable 5.1 leads in every category we measure both in.
Claude Fable 5.1 benchmarks 
Grok 4.5 benchmarks Which to pick for…
The pick's numbers come first. Category scores on the BenchLeader scale (50 is the average model, 15 points one standard deviation). High confidence means a lead of half a standard deviation or more; under one point is called either.
| Use case | Pick | Why | Confidence |
|---|---|---|---|
| Coding | Claude Fable 5.1 | 75 vs 57 category score; Arena WebDev 1743 vs 1553 | High |
| Agents & tool use | Claude Fable 5.1 | 61 vs 57 category score; LiveBench Agentic Coding 66.1% vs 56.5% | Medium |
| Maths | Claude Fable 5.1 | 73 vs 65 category score; Arena Maths 1529 vs 1473 | High |
| Reasoning | Claude Fable 5.1 | 77 vs 69 category score; Arena Hard Prompts 1523 vs 1488 | High |
| Images and other media | Claude Fable 5.1 | 67 vs 63 category score; Arena Vision 1320 vs 1287 | Medium |
| Chat quality (human preference) | Claude Fable 5.1 | 70 vs 65 on Arena votes | Medium |
| Lowest cost | Grok 4.5 | $3.00 vs $20.00 per 1M blended; agentic coding session $0.144 vs $0.800 | – |
| Fastest first answer | Grok 4.5 | 1.5 s (Grok 4.5) vs 180.5 s (Claude Fable 5.1 (max)) to the first answer token | – |
| High volume on a budget | Neither flagship | A smaller model is usually the better fit: Cheapest good LLMs, Fastest LLMs | – |
Key differences
- Claude Fable 5.1 (max) leads on quality: 70.5 vs 60.0.
- Claude Fable 5.1 (max) is stronger in agents & tools, coding, composite, human preference, knowledge, long context, maths, multimodal, reasoning.
- Grok 4.5 is 6.7× cheaper ($3.00 vs $20.00 per 1M blended).
At a glance
| Spec | Claude Fable 5.1 | Grok 4.5 |
|---|---|---|
| Developer | Anthropic | SpaceXAI |
| Released | 1 Sept 2026 | 8 Jul 2026 |
| Context window (tokens) | 1,000,000 | 500,000 |
| Compared at | Claude Fable 5.1 (max) | Grok 4.5 |
| Open weights | No | No |
| Price in / out / cached input per 1M | $10.00 / $50.00 / $0.250 | $2.00 / $6.00 / $0.300 |
Category by category
Category scores on the BenchLeader scale: 50 is the average evaluated model, 15 points is one standard deviation. A gap under one point is called level.
| Category | Claude Fable 5.1 (max) | Grok 4.5 | Leader |
|---|---|---|---|
| Reasoning | 76.8 | 68.7 | Claude Fable 5.1 |
| Coding | 74.9 | 57.1 | Claude Fable 5.1 |
| Agents & tools | 60.5 | 56.5 | Claude Fable 5.1 |
| Maths | 72.9 | 65.4 | Claude Fable 5.1 |
| Knowledge | 77.5 | – | not comparable |
| Human preference | 70.0 | 65.4 | Claude Fable 5.1 |
| Multimodal | 67.1 | 62.9 | Claude Fable 5.1 |
| Long context | 67.8 | – | not comparable |
| Composite | 89.2 | – | not comparable |
Where sources disagree
Across the 19 benchmarks both have, Claude Fable 5.1 leads 19, Grok 4.5 leads 0. Every overall index that rates both puts Claude Fable 5.1 ahead.
| Overall index | Claude Fable 5.1 (max) | Grok 4.5 | Leader |
|---|---|---|---|
| BenchLeader Index | 70.5 | 60.0 | Claude Fable 5.1 |
| AA Intelligence Index v4.3.2 | 53.4 | 38.8† | Claude Fable 5.1 |
| Arena Text | 1503 | 1466 | Claude Fable 5.1 |
Each publisher runs its own tasks, harnesses and effort settings, so their overall verdicts can differ; BenchLeader reconciles them on one scale. † measured at another effort setting of the same model (the publisher did not test the one compared here).
Price, speed and latency
List prices blended at three input tokens per output token. Per-task prices use the token counts on the methodology page; suite cost is what Artificial Analysis paid to run its whole Intelligence Index.
| Measure | Claude Fable 5.1 (max) | Grok 4.5 |
|---|---|---|
| Blended price per 1M tokens | $20.00 | $3.00 |
| Input / output per 1M | $10.00 / $50.00 | $2.00 / $6.00 |
| Cached input per 1M | $0.250 | $0.300 |
| Price per task: chat reply | $0.019 | $0.0026 |
| Price per task: summarize a 30-page report | $0.150 | $0.028 |
| Price per task: code edit | $0.135 | $0.021 |
| Price per task: agentic coding session | $0.800 | $0.144 |
| Price per task: structured extraction | $0.030 | $0.0052 |
| Cost to run a full benchmark suite | $7.63 | – |
| Output speed | 70 tok/s | 54 tok/s |
| Time to first answer | 180.5 s | 1.5 s |
| Time to a complete answer | 187.7 s | – |
Each model is compared at its best-ranked reasoning-effort setting. Claude Fable 5.1 (max) scores 70.5 and takes 181 s to its first answer token; Claude Fable 5.1 (xhigh) scores 69.5 in 91 s, Claude Fable 5.1 (high) scores 69.4 in 18 s. Grok 4.5 scores 60.0 and takes 2 s to its first answer token; Grok 4.5 (high) scores 59.3 in 12 s. Higher effort means more thinking before the answer: better scores, longer waits and more tokens billed. How reasoning effort changes scores and cost.
Every benchmark
143 benchmarks, grouped by category; each name links to the board and its leaders. † measured at another effort setting of the same model, shown for reference and not counted as a win.
| Metric | Publisher | Claude Fable 5.1 (max) | Grok 4.5 |
|---|---|---|---|
| BenchLeader Index | BenchLeader | 70.5 | 60.0 |
| Agents & tools score | BenchLeader | 60.5 | 56.5 |
| Coding score | BenchLeader | 74.9 | 57.1 |
| Composite score | BenchLeader | 89.2 | – |
| Human preference score | BenchLeader | 70.0 | 65.4 |
| Knowledge score | BenchLeader | 77.5 | – |
| Long context score | BenchLeader | 67.8 | – |
| Maths score | BenchLeader | 72.9 | 65.4 |
| Multimodal score | BenchLeader | 67.1 | 62.9 |
| Reasoning score | BenchLeader | 76.8 | 68.7 |
| Blended price $/M | BenchLeader | $20.00 | $3.00 |
| Output speed | BenchLeader | 70 tok/s | 54 tok/s |
| Time to first answer | BenchLeader | 180.5 s | 1.5 s |
| Context window | BenchLeader | 1,000,000 tokens | 500,000 tokens |
| Reasoning | |||
| GPQA Diamond | Epoch AI Benchmarking Hub | – | 93.4%† |
| Humanity's Last Exam | Scale AI / CAIS | 46.5%† | – |
| SimpleBench | SimpleBench | – | 70.0% |
| Arena Hard Prompts | Arena (LMArena) | 1523 | 1488 |
| LiveBench 2.0 Reasoning | LiveBench | 91.7%† | – |
| LiveBench 1.0 Reasoning | LiveBench | 91.7% | 87.2% |
| GPQA Diamond (AA) | Artificial Analysis | 93.7% | 93.1%† |
| Humanity's Last Exam (AA) | Artificial Analysis | 59.1% | 42.7%† |
| GPQA Diamond (Vals) | Vals AI | 93.4%† | 92.9%† |
| Kagi LLM Benchmark | Kagi LLM Benchmark | – | 83.5% |
| ARC-AGI-1 | ARC Prize | 97.5% | 85.7%† |
| ARC-AGI-2 | ARC Prize | 90.0% | 52.6%† |
| ARC-AGI-3 | ARC Prize | – | 0.3%† |
| CritPt | Artificial Analysis | 29.7% | 15.4%† |
| MysteryMechanism | Vals AI | 47.8%† | – |
| Chess Puzzles | Epoch AI Benchmarking Hub | 48.0% | 35.0%† |
| Mystery Game Puzzles | Epoch AI Benchmarking Hub | 58.0% | – |
| LMCA | Epoch AI Benchmarking Hub | 65.5%† | 45.2%† |
| DTBench | Epoch AI Benchmarking Hub | 97.6%† | 96.5%† |
| ForecastBench | ForecastBench | – | 66.1%† |
| Coding | |||
| SciCode | SciCode | 63.1% | 55.0%† |
| WeirdML | WeirdML | 92.9% | 46.4% |
| FrontierCode | Cognition | 50.9%† | 42.4% |
| GSO-Bench | GSO-Bench | 88.2%† | – |
| Arena Coding | Arena (LMArena) | 1538 | 1514 |
Show all 143 benchmarks
| Metric | Publisher | Claude Fable 5.1 (max) | Grok 4.5 |
|---|---|---|---|
| Coding | |||
| Arena WebDev | Arena (LMArena) | 1743 | 1553 |
| LiveBench 2.0 Coding | LiveBench | 97.7%† | – |
| LiveBench 1.0 Coding | LiveBench | 86.4% | 68.6% |
| LiveCodeBench | Vals AI | 90.5%† | 87.3%† |
| IOI | Vals AI | 90.8%† | 40.6%† |
| SWE-bench (Vals) | Vals AI | – | 86.6%† |
| Code Migration | Vals AI | 54.6%† | 36.6%† |
| ProgramBench | Vals AI | 7.0%† | 0.0%† |
| SWE-bench Multimodal | Vals AI | 61.3%† | – |
| Vibe Code Bench 1-100 | Vals AI | 28.0%† | – |
| Vibe Code Bench v1.1 | Vals AI | 90.3%† | 69.0%† |
| SWE Atlas: Codebase QnA | Scale AI SEAL | 60.0%† | – |
| SWE Atlas: Refactoring | Scale AI SEAL | 56.7%† | – |
| SWE Atlas: Test Writing | Scale AI SEAL | 67.0%† | – |
| MirrorCode | Epoch AI Benchmarking Hub | 73.3%† | – |
| Surface Evolver Bench | Epoch AI Benchmarking Hub | – | 74.4%† |
| DeepSWE v1.1 | Epoch AI Benchmarking Hub | – | 53.8%† |
| CursorBench | Cursor | 51.8% | – |
| ALE-Bench | Epoch AI Benchmarking Hub | 2143.2† | 1309.3† |
| FrontierSWE | Epoch AI Benchmarking Hub | 56.3% | – |
| Terminal-Bench 4.0 (AA) | Artificial Analysis | 52.0% | 10.6%† |
| Terminal-Bench 2.1 (AA) | Artificial Analysis | 91.4% | 81.7%† |
| Startrise Frontend | Startrise | 77.1%† | 68.0% |
| FrontierCode 1.1 (AA) | Artificial Analysis | 49.0% | – |
| Agents & tools | |||
| Terminal-Bench | Terminal-Bench | 57.9% | 12.4%† |
| Remote Labor Index | Scale AI / CAIS | 17.9%† | – |
| APEX-Agents | Mercor | 68.6%† | 56.2% |
| Arena Agent | Arena (LMArena) | 13.9 | – |
| LiveBench Long Agentic | LiveBench | 77.9%† | – |
| LiveBench Browser | LiveBench | 89.8%† | – |
| LiveBench Agentic Coding | LiveBench | 66.1% | 56.5% |
| Terminal-Bench 2.1 (Vals) | Vals AI | 85.0%† | 67.8%† |
| MCP Atlas | Scale AI SEAL | 87.2%† | – |
| HiL-Bench | Scale AI SEAL | 61.5%† | – |
| τ³-bench Banking | τ²-bench | – | 47.9%† |
| GDPval-AA v2.1 | Artificial Analysis | 62.7% | – |
| τ³-Banking (AA) | Artificial Analysis | 47.2% | 42.1%† |
| ITBench SRE (AA) | Artificial Analysis | 49.5% | – |
| Analyst Agent (AA) | Artificial Analysis | 57.5% | 35.0%† |
| CUA-bench | Vals AI | 13.2% | – |
| CyberBench | Vals AI | 70.4%† | 71.0%† |
| Finance Agent v2 | Vals AI | 58.9%† | 48.4%† |
| Harvey's Legal Agent Benchmark v1 | Vals AI | 6.7%† | 12.9%† |
| Legal Research Bench | Vals AI | 55.3%† | 38.0%† |
| Robo-bench | Vals AI | 5.8% | – |
| SkillsBench | Vals AI | 61.5%† | 66.0%† |
| SREBench | Vals AI | 22.9%† | 0.8%† |
| Tax Agent Bench | Vals AI | 49.2%† | 24.9%† |
| Terminal-Bench 4.0 (Vals) | Vals AI | 58.1%† | 8.6%† |
| Terminal-Bench Science | Vals AI | 40.0%† | – |
| Time Horizon Index: KSP | Vals AI | 63.3%† | 6.3%† |
| Web Search Index | Vals AI | – | 35.5%† |
| Arena Search | Arena (LMArena) | 1233† | 1206 |
| PostTrainBench | Epoch AI Benchmarking Hub | – | 23.4%† |
| GBAEval | Epoch AI Benchmarking Hub | – | 65.4% |
| Vending-Bench 2 | Andon Labs | 5421.6† | 3887.4 |
| AutomationBench | Artificial Analysis | 59.4% | 57.9%† |
| GDP.pdf (AA) | Artificial Analysis | 26.2% | 18.8%† |
| Harvey LAB-AA v1.1 | Harvey | 6.4% | – |
| EnterpriseOps-Gym | Artificial Analysis | – | 40.8%† |
| AA-Briefcase v1.1 | Artificial Analysis | 1671 | 1278† |
| Terminal-Bench-Science 0.1 (AA) | Artificial Analysis | 43.3% | – |
| CWE-Bench (AA) | Artificial Analysis | 50.8% | – |
| DeepSec-Bench (AA) | Artificial Analysis | 23.5% | – |
| CyberGym end-to-end (AA) | Artificial Analysis | 0.8% | – |
| FACTS Search | – | 79.4% | |
| Maths | |||
| FrontierMath Tiers 1–3 | Epoch AI Benchmarking Hub | 90.2% | 57.2%† |
| FrontierMath Tier 4 | Epoch AI Benchmarking Hub | 87.8% | 24.4%† |
| OTIS Mock AIME | Epoch AI Benchmarking Hub | 100.0% | 97.8%† |
| ProofBench | Vals AI | 100.0% | 31.0%† |
| LiveBench Mathematics | LiveBench | 97.0% | 90.8% |
| Arena Maths | Arena (LMArena) | 1529 | 1473 |
| Knowledge | |||
| SimpleQA Verified | Epoch AI Benchmarking Hub | 70.8% | 48.3%† |
| LiveBench 2.0 Data Analysis | LiveBench | 80.3%† | – |
| LiveBench Research | LiveBench | 82.0%† | – |
| LiveBench 1.0 Data Analysis | LiveBench | 80.3% | 73.0% |
| AA-Omniscience | Artificial Analysis | 43.5 | 25.3† |
| MMLU-Pro | Vals AI | 92.4%† | 89.2%† |
| LegalBench | Vals AI | 88.5%† | 86.0%† |
| CorpFin | Vals AI | – | 67.4%† |
| TaxEval | Vals AI | 76.0%† | 71.7%† |
| PRBench Finance | Scale AI SEAL | 50.8%† | – |
| PRBench Legal | Scale AI SEAL | 51.6%† | – |
| Excel Modeling Benchmark | Vals AI | 76.7%† | 52.9%† |
| Excel Modeling Benchmark v1.1 | Vals AI | 76.7%† | – |
| MedCode | Vals AI | 53.5%† | 43.3%† |
| MedScribe | Vals AI | 91.3%† | 86.9%† |
| Public Benefits Bench v1.1 | Vals AI | 74.9%† | – |
| EBR-bench | Epoch AI Benchmarking Hub | 57.1% | – |
| GDP.pdf | Epoch AI Benchmarking Hub | 27.6% | 14.0%† |
| AA-Omniscience: accuracy | Artificial Analysis | 67.2% | 51.5%† |
| AA-Omniscience: non-hallucination | Artificial Analysis | 27.4% | 45.9%† |
| Instruction following | |||
| LiveBench Language | LiveBench | 89.5% | 82.8% |
| LiveBench Instruction Following | LiveBench | 73.0% | 71.5% |
| Arena Instruction Following | Arena (LMArena) | 1501 | 1461 |
| Human preference | |||
| Arena Text | Arena (LMArena) | 1503 | 1466 |
| Arena Creative Writing | Arena (LMArena) | 1487 | 1452 |
| Arena Multi-turn | Arena (LMArena) | 1488 | 1473 |
| Arena Longer Queries | Arena (LMArena) | 1511 | 1480 |
| Multimodal | |||
| Arena Vision | Arena (LMArena) | 1320 | 1287 |
| LiveBench Design | LiveBench | 83.4%† | – |
| MMMU-Pro | Artificial Analysis | – | 80.4%† |
| MMMU-Pro (Vals) | Vals AI | 90.6%† | 61.8%† |
| MortgageTax | Vals AI | 70.8%† | 61.8%† |
| SAGE | Vals AI | 48.5%† | 35.0%† |
| Blueprint-Bench 2 | Epoch AI Benchmarking Hub | 41.9%† | 27.3% |
| AA-3D | Artificial Analysis | 1135 | – |
| Long context | |||
| AA-LCR | Artificial Analysis | 85.3% | 79.3%† |
| Arena Document | Arena (LMArena) | 1493 | 1464 |
| MLCR | Artificial Analysis | 15.6% | 16.1%† |
| Composite | |||
| Epoch Capabilities Index | Epoch AI Benchmarking Hub | 166.5† | 154.1 |
| LiveBench 2.0 | LiveBench | 85.7%† | – |
| LiveBench 1.0 | LiveBench | 83.4% | 75.8% |
| AA Intelligence Index v4.3.2 | Artificial Analysis | 53.4 | 38.8† |
| Vals RSI Index | Vals AI | 36.1% | – |
| Vals Multimodal Index | Vals AI | – | 63.4%† |
| AA Cyber Index | Artificial Analysis | 25.0 | – |
| Safety & honesty | |||
| FORTRESS | Scale AI SEAL | 13.7%† | – |
Data as of 2026-10-26. Best configuration of each model; every score links to its source on the model pages.
What changed
- Grok 4.5: BenchLeader Index 58.8 → 60.0.
- Claude Fable 5.1 (max): 2 new results (Robo-bench, Vals RSI Index).
- Claude Fable 5.1 (max): 1 score revision.
- Claude Fable 5.1 (max): 1 score revision.
- Claude Fable 5.1 (max): BenchLeader Index 70.0 → 70.6.
- Grok 4.5: 6 new results (LiveBench 2.0, LiveBench Long Agentic, LiveBench 2.0 Coding…).
- Grok 4.5: 1 new result (Startrise Frontend).
- Claude Fable 5.1 (max): 2 score revisions.
- Grok 4.5: 1 score revision.
- Claude Fable 5.1 (max): 1 score revision.
Related comparisons
- Claude Fable 5.1 vs Claude Opus 5.5
- Claude Fable 5.1 vs Gemini 4 Argon
- Claude Fable 5.1 vs Muse Wonder Full
- Grok 4.5 vs Claude Opus 5.5
- Grok 4.5 vs Gemini 4 Argon
- Grok 4.5 vs Muse Wonder Full
- Claude Opus 5 vs Grok 4.5
- Claude Fable 5.1 vs GPT-6.1 Sol
Rankings: Best LLM overall · Best LLM for coding · Best LLM for agents · Best cheap LLMs
Claude Fable 5.1 vs Grok 4.5: questions
- Is Claude Fable 5.1 better than Grok 4.5?
- Claude Fable 5.1 (max) leads on quality: 70.5 vs 60.0. The BenchLeader Index combines every independent quality benchmark; Claude Fable 5.1 (max) is ahead overall as of 2026-10-26, but check the category scores for your use.
- Which is cheaper, Claude Fable 5.1 or Grok 4.5, and will that change?
- Grok 4.5 is cheaper today: $3.00 against $20.00 per million tokens, blended at three input tokens per output token. No price change has been announced for either.
- Is Claude Fable 5.1 better than Grok 4.5 for coding?
- Claude Fable 5.1 scores higher in coding (75 vs 57 on the category index, where 50 is average). On Arena WebDev, the top shared coding benchmark, it is 1743 for Claude Fable 5.1 against 1553 for Grok 4.5.
- Is Claude Fable 5.1 better than Grok 4.5 for agents and tool use?
- Claude Fable 5.1 scores higher in agentic tasks (61 vs 57 on the category index, where 50 is average).
- Which is better for long documents?
- Claude Fable 5.1 accepts more context: 1,000,000 against 500,000 tokens for Grok 4.5.
- Which has lower latency?
- Grok 4.5 answers first: 1.5 s against 180.5 s to the first answer token, as Artificial Analysis measures it. Reasoning effort drives most of this: a higher setting thinks longer before it answers.
- Which is faster, Claude Fable 5.1 or Grok 4.5?
- Claude Fable 5.1 streams faster: 70 against 54 output tokens per second.
- Do independent benchmarks agree on Claude Fable 5.1 vs Grok 4.5?
- Across the 19 benchmarks both have, Claude Fable 5.1 leads 19, Grok 4.5 leads 0. Every overall index that rates both puts Claude Fable 5.1 ahead.
- When was Claude Fable 5.1 released?
- Claude Fable 5.1 was released on 1 Sept 2026.