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Head-to-head comparison

Claude Fable 5.1 vs GLM 5.3 Flash

Claude Fable 5.1 (Anthropic) and GLM 5.3 Flash (Z.ai) 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 24 October 2026

As of 24 October 2026, Claude Fable 5.1 holds the stronger ModelCap Index position (#3 vs #24); GLM 5.3 Flash is 100× cheaper per output token ($0.50/1M vs $50.00/1M); and GLM 5.3 Flash ships open weights.

Which should you choose?

Choose Claude Fable 5.1 if…

  • you want the stronger overall ModelCap Index position — #3 against #24 (85.6 vs 77.3 points).
  • Arena text is your yardstick — 1503 against 1476.
  • Arena coding is your yardstick — 1537 against 1525.
  • LMArena Agent is your yardstick — 13.9% against -1.8%.
  • ARC-AGI-2 is your yardstick — 90.0% against 65.8%.
  • AA Intelligence Index is your yardstick — 53.4 against 41.8.
  • AA Terminal-Bench 2.1 is your yardstick — 91.4% against 84.3%.
  • AA Humanity's Last Exam is your yardstick — 59.1% against 39.9%.
  • Terminal-Bench 4.0 is your yardstick — 57.9% against 35.8%.
  • you want the more recently listed model — Claude Fable 5.1 was listed 1 September 2026, GLM 5.3 Flash 26 August 2026.

Choose GLM 5.3 Flash if…

  • API cost matters — $0.50/1M output tokens against $50.00/1M, about 100× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.15/1M against $10.00/1M.
  • you want to self-host: GLM 5.3 Flash ships open weights while Claude Fable 5.1 is no linked weights.
  • you want provider choice — 34 listed API providers against 4.

Claude Fable 5.1 vs GLM 5.3 Flash: specs, pricing and context

Specification comparison of Claude Fable 5.1 and GLM 5.3 Flash
FieldClaude Fable 5.1AnthropicGLM 5.3 FlashZ.ai
ModelCap Index position#3#24
Index score85.677.3
EvidenceMeasuredMeasured
Input price / 1M tokens$10.00$0.15
Output price / 1M tokens$50.00$0.50
Context window1M tokens1M tokens
Declared route output cap128K944K
API providers listed434
Weight accessNo linked weightsOpen weights
Input modalitiesText, Image, FileText, Image, Video
First listed1 September 202626 August 2026
PublisherAnthropicZ.ai

Evidence: 4 public benchmark observations across 4 boards · 4 public benchmark observations across 4 boards. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Claude Fable 5.1 vs GLM 5.3 Flash

Public benchmark boards where Claude Fable 5.1 or GLM 5.3 Flash has a published result
BoardClaude Fable 5.1GLM 5.3 FlashLeads
Arena textArena (LMArena)15031497–1509Max14761471–1481Not reportedClaude Fable 5.1
Arena codingArena (LMArena)15371527–1548Max15251518–1532Claude Fable 5.1
LMArena AgentLMArena13.9%12.0%–15.9%Max-1.8%-2.4%–-1.1%Claude Fable 5.1
ARC-AGI-2ARC Prize Foundation90.0%Max65.8%MaxClaude Fable 5.1
AA Intelligence IndexArtificial Analysis53.4Reasoning41.8ReasoningClaude Fable 5.1
AA Terminal-Bench 2.1Artificial Analysis91.4%Reasoning84.3%ReasoningClaude Fable 5.1
AA Humanity's Last ExamArtificial Analysis59.1%Reasoning39.9%ReasoningClaude Fable 5.1
Terminal-Bench 4.0Terminal-Bench (Laude Institute)57.9%54.1%–61.6%Claude Code · Max35.8%32.2%–39.3%Claude Code · NoneClaude 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 GLM 5.3 Flash: common questions

Is Claude Fable 5.1 better than GLM 5.3 Flash?

Claude Fable 5.1 ranks higher on the ModelCap Index as of 24 October 2026: #3 against #24. 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 GLM 5.3 Flash?

GLM 5.3 Flash is cheaper on output tokens: $0.50/1M against $50.00/1M. Input tokens are $10.00/1M for Claude Fable 5.1 and $0.15/1M for GLM 5.3 Flash. 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 $0.55 for GLM 5.3 Flash. GLM 5.3 Flash costs 98.8% 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 GLM 5.3 Flash?

Both publish a 1M-token context window. OpenRouter catalogue or provider-endpoint declaration. Limits can vary by provider and prompt length; a model-wide maximum has not been independently verified.

Which is better for coding, Claude Fable 5.1 or GLM 5.3 Flash?

Arena coding: Claude Fable 5.1 1537, GLM 5.3 Flash 1525 — Claude Fable 5.1 leads. AA Terminal-Bench 2.1: Claude Fable 5.1 91.4%, GLM 5.3 Flash 84.3% — Claude Fable 5.1 leads. Terminal-Bench 4.0: Claude Fable 5.1 57.9%, GLM 5.3 Flash 35.8% — Claude Fable 5.1 leads.

Are Claude Fable 5.1 and GLM 5.3 Flash open-weight models?

Claude Fable 5.1: No linked weights. GLM 5.3 Flash: Open weights. Open weights mean the checkpoint can be downloaded and self-hosted under its licence. A missing weight link does not identify every API or chat product that offers a model.

Where can I run Claude Fable 5.1 and GLM 5.3 Flash?

ModelCap currently lists 4 API providers for Claude Fable 5.1 and 34 for GLM 5.3 Flash, 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 GLM 5.3 Flash comparison?

Every figure and ModelCap Index position comes from the same published snapshot dated 24 October 2026. Publication and page updates happen separately; use the snapshot date shown on the page.

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