Model comparison
Claude Fable 5 vs Grok 4.20
Head-to-head evidence from 4 shared benchmark results across 3 categories. Overall scores shown here use the public BenchAlign v5 ranking lane.
Public leaderboard positions: Claude Fable 5 #2 (Supported); Grok 4.20 #88 (Estimated). Intervals and evidence labels describe ranking uncertainty, not a guarantee for a specific workload.
Evidence parity. Claude Fable 5 and Grok 4.20 share 4 comparable benchmark results. 3 of 8 categories are comparable. 30 results are unique to Claude Fable 5; 14 to Grok 4.20.
Updated July 23, 2026- Shared results
- 4
- Claude Fable 5 only
- 30
- Grok 4.20 only
- 14
- Comparable categories
- 3 / 8
Pick Claude Fable 5 if you want the stronger benchmark profile. Grok 4.20 only becomes the better choice if multimodal & grounded is the priority or you want the cheaper token bill.
Confidence note. This is a partial-evidence comparison with 4 shared benchmark results across 3 evidence categories; 3 of 8 categories currently have scoreable aggregates for both models. Treat the verdict as directional until coverage is more balanced.
Why this result
Claude Fable 5 is clearly ahead on the BenchAlign aggregate, 83.68 to 54.68. The gap is large enough that you do not need to squint at the spreadsheet to see the difference.
Claude Fable 5's sharpest advantage is in agentic, where it averages 84.6 against 47.1. The single biggest benchmark swing on the page is Terminal-Bench 2.0, 84.3% to 47.1%. Grok 4.20 does hit back in multimodal & grounded, so the answer changes if that is the part of the workload you care about most.
Claude Fable 5 is also the more expensive model on tokens at $10.00 input / $50.00 output per 1M tokens, versus $2.00 input / $6.00 output per 1M tokens for Grok 4.20. That is roughly 8.3x on output cost alone. Grok 4.20 gives you the larger context window at 2M, compared with 1M+ for Claude Fable 5.
Category breakdown
Exact category averages are shown below. Not measured means BenchLM does not have enough sourced public coverage for that model and category.
| Category | Claude Fable 5 | Δ | Grok 4.20 |
|---|---|---|---|
| Agentic | Claude Fable 584.6 | Margin← 37.5 | Grok 4.2047.1 |
| Coding | Claude Fable 589.2 | Margin← 22.1 | Grok 4.2067.1 |
| Multimodal | Claude Fable 557.9 | Margin→ 12.2 | Grok 4.2070.1 |
| Reasoning | Claude Fable 5Not measured | MarginNo overlap | Grok 4.2053.3 |
Decisive benchmark drivers
The largest measured benchmark gaps in this matchup, with exact reported values.
More
- Source ↗
Terminal-Bench 2.0
AgenticA 84.3%B 47.1%Winner: Claude Fable 5Δ 37.2Terminal-Bench 2.0: Claude Fable 5 scored 84.3%; Grok 4.20 scored 47.1%. Claude Fable 5 wins this benchmark. - Source ↗
SWE-bench Pro
CodingA 80%B 51.8%Winner: Claude Fable 5Δ 28.2SWE-bench Pro: Claude Fable 5 scored 80%; Grok 4.20 scored 51.8%. Claude Fable 5 wins this benchmark. - Source ↗
SWE-bench Verified
CodingA 95%B 76.7%Winner: Claude Fable 5Δ 18.3SWE-bench Verified: Claude Fable 5 scored 95%; Grok 4.20 scored 76.7%. Claude Fable 5 wins this benchmark.
Operational comparison
Runtime and commercial metrics are compared only when both models have a complete sourced value.
| Metric | Claude Fable 5 | Grok 4.20 | Comparison |
|---|---|---|---|
| Input / output priceUSD per 1M tokens | Claude Fable 5$10 input / $50 output | Grok 4.20$2 input / $6 output | Grok 4.20 has the lower combined listed price. |
| Generation speedtokens per second | Claude Fable 5Not available | Grok 4.20233 tok/s | A complete speed comparison is not available. |
| First-answer latencyseconds to first token | Claude Fable 5Not available | Grok 4.2010.33 s | A complete latency comparison is not available. |
| Context windowmaximum listed tokens | Claude Fable 51M+ | Grok 4.202M | Grok 4.20 lists the larger context window. |
Benchmark Deep Dive
AgenticClaude Fable 5 wins15 benchmarks
| Benchmark | Claude Fable 5 | Grok 4.20 | Result |
|---|---|---|---|
| Terminal-Bench 2.0Source | 84.3% | 47.1% | Claude Fable 5 leads |
| OSWorld-VerifiedSource | 85% | — | Not comparable |
| GDPval-AASource | 1748 | — | Not comparable |
| AA Agentic IndexSource | 52.8% | — | Not comparable |
| τ²-bench resultsSource | 98.5% | — | Not comparable |
| GDPval-AASource | 62.4% | — | Not comparable |
| AA BriefcaseSource | 1574 | — | Not comparable |
| AA AutomationBenchSource | 48.6% | — | Not comparable |
| AA EnterpriseOps-GymSource | 51.1% | — | Not comparable |
| AA Harvey LABSource | 93.6% | — | Not comparable |
| AA Tau3 BankingSource | 26.8% | — | Not comparable |
| terminalBenchHardSource | 62.9% | — | Not comparable |
| aaTerminalBench21Source | 84.6% | — | Not comparable |
| DeepSearchQASource | — | 62.8% | Not comparable |
| Gert LabsSource | — | 38.36% | Not comparable |
CodingClaude Fable 5 wins11 benchmarks
| Benchmark | Claude Fable 5 | Grok 4.20 | Result |
|---|---|---|---|
| SWE-bench VerifiedSource | 95% | 76.7% | Claude Fable 5 leads |
| SWE-bench ProSource | 80% | 51.8% | Claude Fable 5 leads |
| FrontierCode 1.1 MainSource | 53.5% | — | Not comparable |
| Terminal-Bench 2.0Source | 84.3% | — | Not comparable |
| cursorBench31Source | 70.6% | — | Not comparable |
| cursorBench32Source | 70.5% | — | Not comparable |
| VulcanBench v3Source | 87.0% | — | Not comparable |
| AA Coding IndexSource | 76.5% | — | Not comparable |
| AA-SciCodeSource | 60.2% | — | Not comparable |
| LiveCodeBench ProSource | — | 74.2% | Not comparable |
| Vibe Code BenchSource | — | 4.06% | Not comparable |
Reasoning3 benchmarks
Knowledge10 benchmarks
| Benchmark | Claude Fable 5 | Grok 4.20 | Result |
|---|---|---|---|
| Artificial Analysis Intelligence IndexSource | 59.9% | — | Not comparable |
| AA-GPQA DiamondSource | 92.6% | — | Not comparable |
| AA-HLESource | 53.3% | — | Not comparable |
| AA-Omniscience IndexSource | 40.2% | — | Not comparable |
| AA-Omniscience AccuracySource | 61.4% | — | Not comparable |
| AA-Omniscience Hallucination RateSource | 54.9% | — | Not comparable |
| GPQA-DSource | — | 88.5% | Not comparable |
| HLE w/o toolsSource | — | 31.6% | Not comparable |
| HealthBench HardSource | — | 20.3% | Not comparable |
| MedXpertQA (Text)Source | — | 50.2% | Not comparable |
MultimodalGrok 4.20 wins8 benchmarks
| Benchmark | Claude Fable 5 | Grok 4.20 | Result |
|---|---|---|---|
| Blueprint-Bench 2Source | 38.6% | — | Not comparable |
| OfficeQA ProSource | 57.9% | — | Not comparable |
| Design Arena WebsiteSource | 1332 | 1257 | Claude Fable 5 leads |
| MMMU-ProSource | — | 75.2% | Not comparable |
| CharXivSource | — | 60.9% | Not comparable |
| ERQASource | — | 54.1% | Not comparable |
| SimpleVQASource | — | 57.4% | Not comparable |
| MedXpertQA (MM)Source | — | 65.8% | Not comparable |
Inst. Following1 benchmarks
| Benchmark | Claude Fable 5 | Grok 4.20 | Result |
|---|---|---|---|
| AA-IFBenchSource | 63.5% | — | Not comparable |
Frequently Asked Questions (4)
Which is better, Claude Fable 5 or Grok 4.20?
Claude Fable 5 is ahead on BenchLM's BenchAlign leaderboard, 83.68 to 54.68. The biggest single separator in this matchup is Terminal-Bench 2.0, where the scores are 84.3% and 47.1%.
Which is better for coding, Claude Fable 5 or Grok 4.20?
Claude Fable 5 has the edge for coding in this comparison, averaging 89.2 versus 67.1. Inside this category, SWE-bench Pro is the benchmark that creates the most daylight between them.
Which is better for agentic tasks, Claude Fable 5 or Grok 4.20?
Claude Fable 5 has the edge for agentic tasks in this comparison, averaging 84.6 versus 47.1. Inside this category, Terminal-Bench 2.0 is the benchmark that creates the most daylight between them.
Which is better for multimodal and grounded tasks, Claude Fable 5 or Grok 4.20?
Grok 4.20 has the edge for multimodal and grounded tasks in this comparison, averaging 70.1 versus 57.9. Inside this category, Design Arena Website is the benchmark that creates the most daylight between them.
Related Comparisons
Choose a model with this week’s evidence
Join 2,000+ readers for ranking moves, pricing changes, and the claims that still need proof.
One email each week. Unsubscribe anytime.