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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 9 September 2026

As of 9 September 2026, GLM 5.3 Flash holds the stronger ModelCap Index position (#11 vs #94); GLM 5.3 Flash is 3.4× cheaper per output token ($0.25/1M vs $0.85/1M); and GLM 5.3 Flash offers the longer context window (1.3M vs 131K tokens).

Which should you choose?

Choose GLM 4.5 Air if…

  • ModelCap publishes no field on which GLM 4.5 Air leads GLM 5.3 Flash for this pair.

Choose GLM 5.3 Flash if…

  • you want the stronger overall ModelCap Index position — #11 against #94 (78.7 vs 41.8 points).
  • API cost matters — $0.25/1M output tokens against $0.85/1M, about 3.4× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.075/1M against $0.13/1M.
  • you need the longer context window — 1.3M tokens against 131K.
  • you want provider choice — 26 listed API providers against 3.
  • Arena coding is your yardstick — 1534 against 1427.
  • AA Humanity's Last Exam is your yardstick — 39.9% against 7.0%.
  • 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#94#11
Index score41.878.7
EvidenceMeasuredMeasured
Input price / 1M tokens$0.13$0.075
Output price / 1M tokens$0.85$0.25
Context window131K tokens1.3M tokens
Max output tokens98K131K
API providers listed326
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 codingArena (LMArena)14271419–143515341517–1551GLM 5.3 Flash
LMArena AgentLMArena—2.0%1.1%–2.9%Only one result
AA Intelligence IndexArtificial Analysis—41.9intelligence-index:v4.3:reasoning-unspecifiedOnly one result
AA Terminal-Bench 2.1Artificial Analysis—84.3%terminal-bench:2.1:terminus-2:e2b:pass-at-1:3-repeats:source-model="GLM-5.3-Flash":reasoning=trueOnly one result
AA τ²-Bench TelecomArtificial Analysis46.5%tau2:telecom:dual-control:pass-at-1:3-repeats:source-model="GLM-4.5-Air":reasoning=true—Only one result
AA Humanity's Last ExamArtificial Analysis7.0%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GLM-4.5-Air":reasoning=true39.9%hle:may-2025:text-only-2158:no-tools:pass-at-1:source-model="GLM-5.3-Flash":reasoning=trueGLM 5.3 Flash

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 9 September 2026: #11 against #94. 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: $0.25/1M against $0.85/1M. Input tokens are $0.13/1M for GLM 4.5 Air 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 $0.69 for GLM 4.5 Air versus $0.28 for GLM 5.3 Flash. GLM 5.3 Flash costs 59.9% 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, GLM 4.5 Air or GLM 5.3 Flash?

GLM 5.3 Flash has the larger context window: 1.3M tokens against 131K.

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 1534 — 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; API-only models are available solely through hosted endpoints.

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 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 GLM 4.5 Air 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.

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