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Comparison · 2 models · Updated Oct 4, 2026

Grok 4.6 vs Claude Fable 5.1

Too close to call on our weighted score (Claude Fable 5.1 66, Grok 4.6 65). The right pick depends on what you value most.

  1. xAI

    Grok 4.6

    Released Aug 12, 2026

    65/100
    • ECI156.6
    • Price$2.00 / $6.00
    • Context500K
    Full specs Remove Grok 4.6

  2. Anthropic

    Claude Fable 5.1

    Released Sep 1, 2026

    66/100
    • ECI164.8
    • Price$10.00 / $50.00
    • Context1M
    Full specs Remove Claude Fable 5.1

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01 — Verdict

Too close to call

It is close. Our weighted score puts them within 1 points (Claude Fable 5.1 66/100, Grok 4.6 65/100), so choose by what matters most for your work: Claude Fable 5.1 for raw capability and Grok 4.6 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Fable 5.1Capabilities Index (ECI): Claude Fable 5.1 164.8 · Grok 4.6 156.6
  • Lowest priceGrok 4.6Grok 4.6 $3.00 · Claude Fable 5.1 $20.00 per 1M tokens (3:1 blend)
  • Longest contextClaude Fable 5.1Claude Fable 5.1 1,000,000 · Grok 4.6 500,000 tokens
  • Widest inputsClaude Fable 5.1Grok 4.6: Text, Images · Claude Fable 5.1: Text, Images, PDFs
  • Self-hostingNo open weightsBoth are available only through APIs
How the score is built
MeasureWeightGrok 4.6Claude Fable 5.1
CapabilityCapabilities Index (ECI)50%8697
Price25%270
Inputs & features15%7080
Context window10%4860
Overall100%65/10066/100
02 — Side by side

Every spec in one table

Highlighted cells lead their row. Dashes mean the data is not published.

Grok 4.6 vs Claude Fable 5.1 specifications side by side
SpecificationGrok 4.6xAIClaude Fable 5.1Anthropic
Capability
Capabilities Index (ECI)156.6164.8 (best)
ECI rank#19 of 148#4 of 148 (best)
GPQA DiamondGraduate-level science questions94.0%—
FrontierMath Tiers 1–3Research-level mathematics66.0%90.2% (best)
OTIS Mock AIME 2024–2025Competition mathematics99.2%100% (best)
SimpleQA VerifiedShort factual questions49.3%70.8% (best)
Price per million tokens
Input$2.00 (best)$10.00
Output$6.00 (best)$50.00
Cached input$0.50$0.25 (best)
Blended (3:1)$3.00 (best)$20.00
Long-context rateOver 200K: $4.00 / $12.00Same rate
Price sourceOfficial xAI APIOfficial Anthropic API
Limits
Context window500,000 tokens1,000,000 tokens (best)
Max output500,000 tokens (best)128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoYes
AudioNoNo
VideoNoNo
ReasoningYeslow · medium · high · xhighYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputYesYes
Availability
WeightsProprietaryProprietary
API model IDgrok-4.6claude-fable-5-1
API providers2929
ReleasedAug 12, 2026Sep 1, 2026
Knowledge cutoffFeb 1, 2026Jun 2026
03 — Cost

What would a month cost?

Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.

  • Grok 4.6$32.00
  • Claude Fable 5.1$200.00
04 — Questions

Which should you choose?

Which is better: Grok 4.6 or Claude Fable 5.1?

It is close. Our weighted score puts them within 1 points (Claude Fable 5.1 66/100, Grok 4.6 65/100), so choose by what matters most for your work: Claude Fable 5.1 for raw capability and Grok 4.6 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Grok 4.6 or Claude Fable 5.1?

Grok 4.6 is cheaper at $2.00 input / $6.00 output per million tokens (official xAI API price). Claude Fable 5.1 costs $10.00 input / $50.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $3.00 per million tokens for Grok 4.6 versus $20.00 for Claude Fable 5.1 (6.7× as much).

Which scores higher on benchmarks?

Claude Fable 5.1 scores higher on the Capabilities Index (ECI): Claude Fable 5.1 164.8 (#4 of 148) and Grok 4.6 156.6 (#19 of 148). Their confidence ranges do not overlap (161.8–169.1 vs 154.7–158.9), so the gap is a real one. On individual benchmarks: FrontierMath Tiers 1–3 — Claude Fable 5.1 90.2%, Grok 4.6 66.0%; OTIS Mock AIME 2024–2025 — Claude Fable 5.1 100%, Grok 4.6 99.2%; SimpleQA Verified — Claude Fable 5.1 70.8%, Grok 4.6 49.3%.

Which is better for coding?

There are no published SWE-bench Verified results for Grok 4.6 and Claude Fable 5.1 yet, so there is no like-for-like coding score. On overall capability, Claude Fable 5.1 leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.

Which has the bigger context window?

Claude Fable 5.1 has the largest context window at 1,000,000 tokens, against 500,000 for Grok 4.6. Maximum output per response: Grok 4.6 up to 500,000, Claude Fable 5.1 up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Grok 4.6 accepts text and images; Claude Fable 5.1 accepts text, images and PDFs. Claude Fable 5.1 handles the widest range of inputs.

Are any of these open source?

No. Grok 4.6 and Claude Fable 5.1 are proprietary and only available through APIs and apps.

Which is newer?

Claude Fable 5.1 is the newest, released Sep 1, 2026. Grok 4.6 came out Aug 12, 2026. Knowledge cutoff: Grok 4.6 Feb 1, 2026, Claude Fable 5.1 Jun 2026.

How do you decide the winner?

Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.

05 — Keep comparing

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