Compare / head-to-head
Claude Fable 5.1vsGrok 4.20 Reasoning
Claude Fable 5.1 leads 4 of 4 shared benchmarks. Grok 4.20 Reasoning is 16x cheaper per token. Both offer a 1M-token context window.
Benchmarks from cited public sources; pricing from official pages; status from official provider feeds.
Shared benchmarks
4 – 0
Claude Fable 5.1 leads
Cheaper per token
Grok 4.20 Reasoning
16x cheaper, input + output
Larger context
Tie
both 1M tokens
Provider uptime (30d)
100% · —
Anthropic · xAI
Claude Fable 5.1
Anthropic · released 2026-09-01
textvision
Grok 4.20 Reasoning
xAI · released 2026-03-09
textvision
Quality
Benchmark matrix
4 shared · 4 only Claude Fable 5.1 · 1 only Grok 4.20 Reasoning| Benchmark | Claude Fable 5.1 | Grok 4.20 Reasoning | Δ | Edge |
|---|---|---|---|---|
| Reported by both · 4 | ||||
| FrontierMath Tier 4 v2 (Epoch AI run) | 87.8% ↗epoch | 17.1% ↗epoch | +70.7 pt | Claude Fable 5.1 |
| FrontierMath Tiers 1-3 v2 (Epoch AI run) | 90.2% ↗epoch | 44.9% ↗epoch | +45.3 pt | Claude Fable 5.1 |
| OTIS Mock AIME 2024-2025 (Epoch AI run) | 100% ↗epoch | 92.2% ↗epoch | +7.8 pt | Claude Fable 5.1 |
| SimpleQA Verified | 70.8% ↗epoch | 30.2% ↗epoch | +40.6 pt | Claude Fable 5.1 |
| Only Claude Fable 5.1 reports · 4 | ||||
| Humanity's Last Exam (no tools) | 60.9% ↗ | not reported | — | — |
| CursorBench 3.2.0 | 73.4% ↗ | not reported | — | — |
| GDPval-AA v2 | 1853 ↗ | not reported | — | — |
| Terminal-Bench Science 0.1 | 52.6% ↗ | not reported | — | — |
| Only Grok 4.20 Reasoning reports · 1 | ||||
| GPQA Diamond | not reported | 89.3% ↗epoch | — | — |
Scores tagged "epoch" or "matharena" are independent runs, used only where the lab has not published its own; ⚠ marks rows MathArena flags as released after the competition. Higher is better on every row. Δ is Claude Fable 5.1 minus Grok 4.20 Reasoning in the benchmark's own unit. "Not reported" means the lab has not published that figure; it is not a zero. ↗ opens the source.
Specs & pricing
Side by side
Official pricing pages and model cards| Spec | Claude Fable 5.1 | Grok 4.20 Reasoning | Edge |
|---|---|---|---|
| Context window | 1M tokens | 1M tokens | Tie |
| Max output | 128K tokens | — | — |
| Input price / 1M | $10 ↗ | $1.25 ↗ | Grok 4.20 Reasoning |
| Output price / 1M | $50 ↗ | $2.5 ↗ | Grok 4.20 Reasoning |
| Cached input / 1M | $0.25 ↗ | $0.2 ↗ | Grok 4.20 Reasoning |
| Input + output / 1M Lower is cheaper. List prices; batch, tool and regional fees excluded. | $60 | $3.75 | Grok 4.20 Reasoning |
| Modalities | text · vision | text · vision | Tie |
| Released | 2026-09-01 | 2026-03-09 | — |
| Cited benchmark scores | 8 | 5 | — |
Reliability
Provider status
Last 60 days · refreshed daily on this page · live on /statusMore matchups
Claude Fable 5.1 vs …
Models sharing the most benchmarksMore matchups
Grok 4.20 Reasoning vs …
Models sharing the most benchmarksBuilt by Respan
Which one wins on your data?
Public benchmarks are a starting point. Run Claude Fable 5.1 and Grok 4.20 Reasoning on your own prompts with Respan evals, or route to either through one gateway key with automatic failover.