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Head-to-head comparison

Claude Opus 5.5 vs GLM 5.3 Flash

Claude Opus 5.5 (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 6 November 2026

As of 6 November 2026, Claude Opus 5.5 holds the stronger ModelCap Index position (#1 vs #22); GLM 5.3 Flash is 40× cheaper per output token ($0.50/1M vs $20.00/1M); and GLM 5.3 Flash ships open weights.

Which should you choose?

Choose Claude Opus 5.5 if…

  • you want the stronger overall ModelCap Index position — #1 against #22 (87.7 vs 78.2 points).
  • Arena text is your yardstick — 1509 against 1477.
  • Arena coding is your yardstick — 1551 against 1526.
  • LMArena Agent is your yardstick — 20.1% against -2.4%.
  • ARC-AGI-2 is your yardstick — 93.3% against 65.8%.
  • AA Intelligence Index is your yardstick — 59.1 against 27.8.
  • Terminal-Bench 4.0 is your yardstick — 64.9% against 35.8%.
  • you want the more recently listed model — Claude Opus 5.5 was listed 22 September 2026, GLM 5.3 Flash 26 August 2026.

Choose GLM 5.3 Flash if…

  • API cost matters — $0.50/1M output tokens against $20.00/1M, about 40× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.15/1M against $4.00/1M.
  • you want to self-host: GLM 5.3 Flash ships open weights while Claude Opus 5.5 is no linked weights.
  • you want provider choice — 36 listed API providers against 5.

Claude Opus 5.5 vs GLM 5.3 Flash: specs, pricing and context

Specification comparison of Claude Opus 5.5 and GLM 5.3 Flash
FieldClaude Opus 5.5AnthropicGLM 5.3 FlashZ.ai
ModelCap Index position#1#22
Index score87.778.2
EvidenceMeasuredMeasured
Input price / 1M tokens$4.00$0.15
Output price / 1M tokens$20.00$0.50
Context window1M tokens1M tokens
Declared route output cap128K944K
API providers listed536
Weight accessNo linked weightsOpen weights
Input modalitiesText, Image, FileText, Image, Video
First listed22 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 Opus 5.5 vs GLM 5.3 Flash

Public benchmark boards where Claude Opus 5.5 or GLM 5.3 Flash has a published result
BoardClaude Opus 5.5GLM 5.3 FlashLeads
Arena textArena (LMArena)15091502–1515High14771472–1481Not reportedClaude Opus 5.5
Arena codingArena (LMArena)15511538–1563High15261519–1533Claude Opus 5.5
LMArena AgentLMArena20.1%18.1%–22.2%Max-2.4%-3.1%–-1.7%Claude Opus 5.5
ARC-AGI-2ARC Prize Foundation93.3%High65.8%MaxClaude Opus 5.5
AA Intelligence IndexArtificial Analysis59.1Max27.8ReasoningClaude Opus 5.5
Terminal-Bench 4.0Terminal-Bench (Laude Institute)64.9%61.7%–68.0%Claude Code · Max35.8%32.2%–39.3%Claude Code · NoneClaude Opus 5.5

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 Opus 5.5 vs GLM 5.3 Flash: common questions

Is Claude Opus 5.5 better than GLM 5.3 Flash?

Claude Opus 5.5 ranks higher on the ModelCap Index as of 6 November 2026: #1 against #22. 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 Opus 5.5 cheaper than GLM 5.3 Flash?

GLM 5.3 Flash is cheaper on output tokens: $0.50/1M against $20.00/1M. Input tokens are $4.00/1M for Claude Opus 5.5 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 $18.00 for Claude Opus 5.5 versus $0.55 for GLM 5.3 Flash. GLM 5.3 Flash costs 96.9% 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 Opus 5.5 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 Opus 5.5 or GLM 5.3 Flash?

Arena coding: Claude Opus 5.5 1551, GLM 5.3 Flash 1526 — Claude Opus 5.5 leads. Terminal-Bench 4.0: Claude Opus 5.5 64.9%, GLM 5.3 Flash 35.8% — Claude Opus 5.5 leads.

Are Claude Opus 5.5 and GLM 5.3 Flash open-weight models?

Claude Opus 5.5: 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 Opus 5.5 and GLM 5.3 Flash?

ModelCap currently lists 5 API providers for Claude Opus 5.5 and 36 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 Opus 5.5 vs GLM 5.3 Flash comparison?

Every figure and ModelCap Index position comes from the same published snapshot dated 6 November 2026. Publication and page updates happen separately; use the snapshot date shown on the page.

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