Skip to content
ModelCap

Head-to-head comparison

Claude Fable 5.1 vs GLM 5.3

Claude Fable 5.1 (Anthropic) and GLM 5.3 (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 9 September 2026

As of 9 September 2026, Claude Fable 5.1 holds the stronger ModelCap Index position (#3 vs #8); and GLM 5.3 is 11.4× cheaper per output token ($4.40/1M vs $50.00/1M).

Which should you choose?

Choose Claude Fable 5.1 if…

  • you want the stronger overall ModelCap Index position — #3 against #8 (87.7 vs 82.1 points).
  • LMArena Agent is your yardstick — 14.5% against 2.6%.
  • AA Intelligence Index is your yardstick — 53.4 against 44.9.
  • AA Terminal-Bench 2.1 is your yardstick — 91.4% against 83.9%.
  • AA Humanity's Last Exam is your yardstick — 59.1% against 42.3%.
  • Terminal-Bench 4.0 is your yardstick — 57.9% against 41.8%.
  • you want the more recently listed model — Claude Fable 5.1 was listed 1 September 2026, GLM 5.3 18 August 2026.

Choose GLM 5.3 if…

  • API cost matters — $4.40/1M output tokens against $50.00/1M, about 11.4× cheaper.
  • your workload is prompt-heavy — input tokens cost $1.40/1M against $10.00/1M.
  • you want provider choice — 26 listed API providers against 4.
  • Arena coding is your yardstick — 1528 against 1517.

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

Specification comparison of Claude Fable 5.1 and GLM 5.3
FieldClaude Fable 5.1AnthropicGLM 5.3Z.ai
ModelCap Index position#3#8
Index score87.782.1
EvidenceMeasuredMeasured
Input price / 1M tokens$10.00$1.40
Output price / 1M tokens$50.00$4.40
Context window1M tokens1M tokens
Max output tokens128K944K
API providers listed426
Weight accessAPI onlyRestricted license
Input modalitiesText, Image, FileText
First listed1 September 202618 August 2026
PublisherAnthropicZ.ai

Evidence: 5 public benchmark observations across 5 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

Public benchmark boards where Claude Fable 5.1 or GLM 5.3 has a published result
BoardClaude Fable 5.1GLM 5.3Leads
Arena codingArena (LMArena)15171491–1542Max15281514–1541MaxGLM 5.3
LMArena AgentLMArena14.5%12.6%–16.4%Max2.6%1.9%–3.2%MaxClaude Fable 5.1
ARC-AGI-2ARC Prize Foundation90.0%Max—Only one result
AA Intelligence IndexArtificial Analysis53.4intelligence-index:v4.3:reasoning-unspecified44.9intelligence-index:v4.3:maxClaude Fable 5.1
AA Terminal-Bench 2.1Artificial Analysis91.4%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="Claude Fable 5.1 (max with fallback)":reasoning=true83.9%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="GLM-5.3 (max)":reasoning=trueClaude 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 (max with fallback)":reasoning=true42.3%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GLM-5.3 (max)":reasoning=trueClaude Fable 5.1
Terminal-Bench 4.0Terminal-Bench (Laude Institute)57.9%54.1%–61.6%Claude Code · Max41.8%38.6%–45.1%Claude Code · MaxClaude 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: common questions

Is Claude Fable 5.1 better than GLM 5.3?

Claude Fable 5.1 ranks higher on the ModelCap Index as of 9 September 2026: #3 against #8. 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?

GLM 5.3 is cheaper on output tokens: $4.40/1M against $50.00/1M. Input tokens are $10.00/1M for Claude Fable 5.1 and $1.40/1M for GLM 5.3. 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 $5.00 for GLM 5.3. GLM 5.3 costs 88.9% 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?

Both publish a 1M-token context window.

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

Arena coding: Claude Fable 5.1 1517, GLM 5.3 1528 — GLM 5.3 leads. AA Terminal-Bench 2.1: Claude Fable 5.1 91.4%, GLM 5.3 83.9% — Claude Fable 5.1 leads. Terminal-Bench 4.0: Claude Fable 5.1 57.9%, GLM 5.3 41.8% — Claude Fable 5.1 leads.

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

Claude Fable 5.1: API only. GLM 5.3: Restricted license. 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 GLM 5.3?

ModelCap currently lists 4 API providers for Claude Fable 5.1 and 26 for GLM 5.3, 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 comparison?

Every figure comes from the sealed ModelCap dataset published 9 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.

Explore further