Skip to content
ModelCap

Head-to-head comparison

Claude Sonnet 5 vs GLM 5.3 Flash

Claude Sonnet 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 9 September 2026

As of 9 September 2026, GLM 5.3 Flash holds the stronger ModelCap Index position (#11 vs #18); GLM 5.3 Flash is 40× cheaper per output token ($0.25/1M vs $10.00/1M); GLM 5.3 Flash offers the longer context window (1.3M vs 1M tokens); and GLM 5.3 Flash ships open weights.

Which should you choose?

Choose Claude Sonnet 5 if…

  • LMArena Agent is your yardstick — 6.3% against 2.0%.
  • AA Humanity's Last Exam is your yardstick — 41.3% against 39.9%.

Choose GLM 5.3 Flash if…

  • you want the stronger overall ModelCap Index position — #11 against #18 (78.7 vs 75.6 points).
  • API cost matters — $0.25/1M output tokens against $10.00/1M, about 40× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.075/1M against $2.00/1M.
  • you need the longer context window — 1.3M tokens against 1M.
  • you want to self-host: GLM 5.3 Flash ships open weights while Claude Sonnet 5 is api only.
  • you want provider choice — 26 listed API providers against 5.
  • Arena coding is your yardstick — 1534 against 1521.
  • AA Intelligence Index is your yardstick — 41.9 against 38.4.
  • AA Terminal-Bench 2.1 is your yardstick — 84.3% against 80.5%.
  • you want the more recently listed model — GLM 5.3 Flash was listed 26 August 2026, Claude Sonnet 5 30 June 2026.

Claude Sonnet 5 vs GLM 5.3 Flash: specs, pricing and context

Specification comparison of Claude Sonnet 5 and GLM 5.3 Flash
FieldClaude Sonnet 5AnthropicGLM 5.3 FlashZ.ai
ModelCap Index position#18#11
Index score75.678.7
EvidenceMeasuredMeasured
Input price / 1M tokens$2.00$0.075
Output price / 1M tokens$10.00$0.25
Context window1M tokens1.3M tokens
Max output tokens128K131K
API providers listed526
Weight accessAPI onlyOpen weights
Input modalitiesText, Image, FileText, Image, Video
First listed30 June 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 Sonnet 5 vs GLM 5.3 Flash

Public benchmark boards where Claude Sonnet 5 or GLM 5.3 Flash has a published result
BoardClaude Sonnet 5GLM 5.3 FlashLeads
Arena codingArena (LMArena)15211514–1529High15341517–1551GLM 5.3 Flash
LMArena AgentLMArena6.3%4.4%–8.2%High2.0%1.1%–2.9%Claude Sonnet 5
AA Intelligence IndexArtificial Analysis38.4intelligence-index:v4.3:max41.9intelligence-index:v4.3:reasoning-unspecifiedGLM 5.3 Flash
AA Terminal-Bench 2.1Artificial Analysis80.5%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="Claude Sonnet 5 (max)":reasoning=true84.3%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="GLM-5.3-Flash":reasoning=trueGLM 5.3 Flash
AA Humanity's Last ExamArtificial Analysis41.3%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="Claude Sonnet 5 (max)":reasoning=true39.9%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GLM-5.3-Flash":reasoning=trueClaude Sonnet 5
Terminal-Bench 4.0Terminal-Bench (Laude Institute)12.4%9.4%–15.5%Claude Code · Max—Only one result

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 Sonnet 5 vs GLM 5.3 Flash: common questions

Is Claude Sonnet 5 better than GLM 5.3 Flash?

GLM 5.3 Flash ranks higher on the ModelCap Index as of 9 September 2026: #11 against #18. 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 Sonnet 5 cheaper than GLM 5.3 Flash?

GLM 5.3 Flash is cheaper on output tokens: $0.25/1M against $10.00/1M. Input tokens are $2.00/1M for Claude Sonnet 5 and $0.075/1M 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 $9.00 for Claude Sonnet 5 versus $0.28 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 Sonnet 5 or GLM 5.3 Flash?

GLM 5.3 Flash has the larger context window: 1.3M tokens against 1M.

Which is better for coding, Claude Sonnet 5 or GLM 5.3 Flash?

Arena coding: Claude Sonnet 5 1521, GLM 5.3 Flash 1534 — GLM 5.3 Flash leads. AA Terminal-Bench 2.1: Claude Sonnet 5 80.5%, GLM 5.3 Flash 84.3% — GLM 5.3 Flash leads.

Are Claude Sonnet 5 and GLM 5.3 Flash open-weight models?

Claude Sonnet 5: API only. GLM 5.3 Flash: Open weights. 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 Sonnet 5 and GLM 5.3 Flash?

ModelCap currently lists 5 API providers for Claude Sonnet 5 and 26 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 Sonnet 5 vs GLM 5.3 Flash 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