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Head-to-head comparison

Claude Fable 5.1 vs Grok 4.7

Claude Fable 5.1 (Anthropic) and Grok 4.7 (xAI) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 22 September 2026

As of 22 September 2026, Claude Fable 5.1 holds the stronger ModelCap Index position (#1 vs #4); Grok 4.7 is 10.4× cheaper per output token ($4.80/1M vs $50.00/1M); and Claude Fable 5.1 offers the longer context window (1M vs 500K tokens).

Which should you choose?

Choose Claude Fable 5.1 if…

  • you want the stronger overall ModelCap Index position — #1 against #4 (86.8 vs 84.9 points).
  • you need the longer context window — 1M tokens against 500K.
  • you want provider choice — 4 listed API providers against 1.
  • AA Intelligence Index is your yardstick — 53.4 against 46.4.
  • AA Humanity's Last Exam is your yardstick — 59.1% against 43.1%.
  • Terminal-Bench 4.0 is your yardstick — 57.9% against 37.6%.

Choose Grok 4.7 if…

  • API cost matters — $4.80/1M output tokens against $50.00/1M, about 10.4× cheaper.
  • your workload is prompt-heavy — input tokens cost $1.60/1M against $10.00/1M.
  • you want the more recently listed model — Grok 4.7 was listed 21 September 2026, Claude Fable 5.1 1 September 2026.

Claude Fable 5.1 vs Grok 4.7: specs, pricing and context

Specification comparison of Claude Fable 5.1 and Grok 4.7
FieldClaude Fable 5.1AnthropicGrok 4.7xAI
ModelCap Index position#1#4
Index score86.884.9
EvidenceMeasuredMeasured
Input price / 1M tokens$10.00$1.60
Output price / 1M tokens$50.00$4.80
Context window1M tokens500K tokens
Max output tokens128K450K
API providers listed41
Weight accessAPI onlyAPI only
Input modalitiesText, Image, FileText, Image, File
First listed1 September 202621 September 2026
PublisherAnthropicxAI

Evidence: 5 public benchmark observations across 5 boards · 1 public benchmark observation across 1 board. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Claude Fable 5.1 vs Grok 4.7

Public benchmark boards where Claude Fable 5.1 or Grok 4.7 has a published result
BoardClaude Fable 5.1Grok 4.7Leads
Arena codingArena (LMArena)15191501–1537Max—Only one result
LMArena AgentLMArena13.7%12.0%–15.4%Max—Only one result
ARC-AGI-2ARC Prize Foundation90.0%Max—Only one result
AA Intelligence IndexArtificial Analysis53.4intelligence-index:v4.3:reasoning-unspecified46.4intelligence-index:v4.3:xhighClaude Fable 5.1
AA Humanity's Last ExamArtificial Analysis59.1%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="Claude Fable 5.1 (Adaptive Reasoning, Max Effort, Default Fallback)":reasoning=true43.1%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="Grok 4.7 (xhigh)":reasoning=trueClaude Fable 5.1
Terminal-Bench 4.0Terminal-Bench (Laude Institute)57.9%54.1%–61.6%Claude Code · Max37.6%34.0%–41.1%Grok Build · X-HighClaude Fable 5.1

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

Claude Fable 5.1 vs Grok 4.7: common questions

Is Claude Fable 5.1 better than Grok 4.7?

Claude Fable 5.1 ranks higher on the ModelCap Index as of 22 September 2026: #1 against #4. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it. Their published uncertainty intervals overlap, so the rank difference alone does not establish a reliable capability advantage for your workload.

Is Claude Fable 5.1 cheaper than Grok 4.7?

Grok 4.7 is cheaper on output tokens: $4.80/1M against $50.00/1M. Input tokens are $10.00/1M for Claude Fable 5.1 and $1.60/1M for Grok 4.7. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens. For 1,000 requests with 2,000 input and 500 output tokens each (2M input + 0.5M output), the listed-rate estimate is $45.00 for Claude Fable 5.1 versus $5.60 for Grok 4.7. Grok 4.7 costs 87.6% less in this scenario. This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the selected endpoint before budgeting.

Which has the bigger context window, Claude Fable 5.1 or Grok 4.7?

Claude Fable 5.1 has the larger context window: 1M tokens against 500K.

Which is better for coding, Claude Fable 5.1 or Grok 4.7?

Terminal-Bench 4.0: Claude Fable 5.1 57.9%, Grok 4.7 37.6% — Claude Fable 5.1 leads.

Are Claude Fable 5.1 and Grok 4.7 open-weight models?

Claude Fable 5.1: API only. Grok 4.7: API only. Open weights mean the checkpoint can be downloaded and self-hosted under its licence; API-only models are available solely through hosted endpoints.

Where can I run Claude Fable 5.1 and Grok 4.7?

ModelCap currently lists 4 API providers for Claude Fable 5.1 and 1 for Grok 4.7, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Claude Fable 5.1 vs Grok 4.7 comparison?

Every figure comes from the sealed ModelCap dataset published 22 September 2026; the page re-renders within a minute of each data refresh, and the ModelCap Index positions are the same ones shown on the live rankings.

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