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ModelCap

Head-to-head comparison

GLM 4.5 Air vs GLM 5.3 Flash

GLM 4.5 Air (Z.ai) 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, GLM 5.3 Flash holds the stronger ModelCap Index position (#24 vs #136); GLM 5.3 Flash is 1.7× cheaper per output token ($0.50/1M vs $0.85/1M); and GLM 5.3 Flash offers the longer context window (1M vs 131K tokens).

Which should you choose?

Choose GLM 4.5 Air if…

  • your workload is prompt-heavy — input tokens cost $0.13/1M against $0.15/1M.

Choose GLM 5.3 Flash if…

  • you want the stronger overall ModelCap Index position — #24 against #136 (77.3 vs 44.9 points).
  • API cost matters — $0.50/1M output tokens against $0.85/1M, about 1.7× cheaper.
  • you need the longer context window — 1M tokens against 131K.
  • you want provider choice — 34 listed API providers against 3.
  • Arena text is your yardstick — 1476 against 1373.
  • Arena coding is your yardstick — 1525 against 1427.
  • you want the more recently listed model — GLM 5.3 Flash was listed 26 August 2026, GLM 4.5 Air 25 July 2025.

GLM 4.5 Air vs GLM 5.3 Flash: specs, pricing and context

Specification comparison of GLM 4.5 Air and GLM 5.3 Flash
FieldGLM 4.5 AirZ.aiGLM 5.3 FlashZ.ai
ModelCap Index position#136#24
Index score44.977.3
EvidenceMeasuredMeasured
Input price / 1M tokens$0.13$0.15
Output price / 1M tokens$0.85$0.50
Context window131K tokens1M tokens
Declared route output cap98K944K
API providers listed334
Weight accessOpen weightsOpen weights
Input modalitiesTextText, Image, Video
First listed25 July 202526 August 2026
PublisherZ.aiZ.ai

Evidence: 2 public benchmark observations across 2 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: GLM 4.5 Air vs GLM 5.3 Flash

Public benchmark boards where GLM 4.5 Air or GLM 5.3 Flash has a published result
BoardGLM 4.5 AirGLM 5.3 FlashLeads
Arena textArena (LMArena)13731369–1377Not reported14761471–1481Not reportedGLM 5.3 Flash
Arena codingArena (LMArena)14271419–143415251518–1532GLM 5.3 Flash
LMArena AgentLMArena—-1.8%-2.4%–-1.1%Only one result
ARC-AGI-2ARC Prize Foundation—65.8%MaxOnly one result
AA Intelligence IndexArtificial Analysis—41.8ReasoningOnly one result
AA Terminal-Bench 2.1Artificial Analysis—84.3%ReasoningOnly one result
AA Humanity's Last ExamArtificial Analysis—39.9%ReasoningOnly one result
Terminal-Bench 4.0Terminal-Bench (Laude Institute)—35.8%32.2%–39.3%Claude Code · NoneOnly 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.

GLM 4.5 Air vs GLM 5.3 Flash: common questions

Is GLM 4.5 Air better than GLM 5.3 Flash?

GLM 5.3 Flash ranks higher on the ModelCap Index as of 24 October 2026: #24 against #136. 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 do not overlap, but the aggregate Index does not predict performance on every task; compare the relevant benchmark configurations before choosing.

Is GLM 4.5 Air cheaper than GLM 5.3 Flash?

GLM 5.3 Flash is cheaper on output tokens: $0.50/1M against $0.85/1M. Input tokens are $0.13/1M for GLM 4.5 Air 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 $0.69 for GLM 4.5 Air versus $0.55 for GLM 5.3 Flash. GLM 5.3 Flash costs 19.7% 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, GLM 4.5 Air or GLM 5.3 Flash?

GLM 5.3 Flash has the larger context window: 1M tokens against 131K. 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, GLM 4.5 Air or GLM 5.3 Flash?

Arena coding: GLM 4.5 Air 1427, GLM 5.3 Flash 1525 — GLM 5.3 Flash leads.

Are GLM 4.5 Air and GLM 5.3 Flash open-weight models?

GLM 4.5 Air: Open 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 GLM 4.5 Air and GLM 5.3 Flash?

ModelCap currently lists 3 API providers for GLM 4.5 Air 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 GLM 4.5 Air 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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