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Head-to-head comparison

GPT-5.6 Terra vs GLM 5.3

GPT-5.6 Terra (OpenAI) 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 2 October 2026

As of 2 October 2026, GLM 5.3 holds the stronger ModelCap Index position (#11 vs #22); and GLM 5.3 is 2.7× cheaper per output token ($4.40/1M vs $12.00/1M).

Which should you choose?

Choose GPT-5.6 Terra if…

  • AA Terminal-Bench 2.1 is your yardstick — 88.0% against 83.9%.
  • AA Humanity's Last Exam is your yardstick — 42.9% against 42.3%.

Choose GLM 5.3 if…

  • you want the stronger overall ModelCap Index position — #11 against #22 (80.0 vs 76.2 points).
  • API cost matters — $4.40/1M output tokens against $12.00/1M, about 2.7× cheaper.
  • your workload is prompt-heavy — input tokens cost $1.40/1M against $2.00/1M.
  • you want provider choice — 32 listed API providers against 3.
  • Arena text is your yardstick — 1479 against 1465.
  • Arena coding is your yardstick — 1521 against 1515.
  • LMArena Agent is your yardstick — 2.6% against 0.8%.
  • AA Intelligence Index is your yardstick — 44.8 against 42.1.
  • Terminal-Bench 4.0 is your yardstick — 41.8% against 21.5%.
  • you want the more recently listed model — GLM 5.3 was listed 18 August 2026, GPT-5.6 Terra 9 July 2026.

GPT-5.6 Terra vs GLM 5.3: specs, pricing and context

Specification comparison of GPT-5.6 Terra and GLM 5.3
FieldGPT-5.6 TerraOpenAIGLM 5.3Z.ai
ModelCap Index position#22#11
Index score76.280.0
EvidenceMeasuredMeasured
Input price / 1M tokens$2.00$1.40
Output price / 1M tokens$12.00$4.40
Context window1M tokens1M tokens
Declared route output cap128K131K
API providers listed332
Weight accessNo linked weightsRestricted license
Input modalitiesFile, Image, TextText
First listed9 July 202618 August 2026
PublisherOpenAIZ.ai

Evidence: 6 public benchmark observations across 6 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: GPT-5.6 Terra vs GLM 5.3

Public benchmark boards where GPT-5.6 Terra or GLM 5.3 has a published result
BoardGPT-5.6 TerraGLM 5.3Leads
Arena textArena (LMArena)14651461–1470X-High14791474–1485MaxGLM 5.3
Arena codingArena (LMArena)15151508–1522X-High15211512–1531MaxGLM 5.3
LMArena AgentLMArena0.8%-0.4%–2.1%X-High2.6%1.9%–3.3%MaxGLM 5.3
ARC-AGI-2ARC Prize Foundation83.9%Max—Only one result
ARC-AGI-3ARC Prize Foundation0.8%Max—Only one result
AA Intelligence IndexArtificial Analysis42.1Max44.8MaxGLM 5.3
AA Terminal-Bench 2.1Artificial Analysis88.0%Max83.9%MaxGPT-5.6 Terra
AA τ²-Bench TelecomArtificial Analysis86.3%Max—Only one result
AA Humanity's Last ExamArtificial Analysis42.9%Max42.3%MaxGPT-5.6 Terra
Terminal-Bench 4.0Terminal-Bench (Laude Institute)21.5%18.3%–24.8%Codex · Max41.8%38.6%–45.1%Claude Code · MaxGLM 5.3

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.

GPT-5.6 Terra vs GLM 5.3: common questions

Is GPT-5.6 Terra better than GLM 5.3?

GLM 5.3 ranks higher on the ModelCap Index as of 2 October 2026: #11 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 GPT-5.6 Terra cheaper than GLM 5.3?

GLM 5.3 is cheaper on output tokens: $4.40/1M against $12.00/1M. Input tokens are $2.00/1M for GPT-5.6 Terra 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 $10.00 for GPT-5.6 Terra versus $5.00 for GLM 5.3. GLM 5.3 costs 50.0% 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, GPT-5.6 Terra or GLM 5.3?

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, GPT-5.6 Terra or GLM 5.3?

Arena coding: GPT-5.6 Terra 1515, GLM 5.3 1521 — GLM 5.3 leads. AA Terminal-Bench 2.1: GPT-5.6 Terra 88.0%, GLM 5.3 83.9% — GPT-5.6 Terra leads. Terminal-Bench 4.0: GPT-5.6 Terra 21.5%, GLM 5.3 41.8% — GLM 5.3 leads.

Are GPT-5.6 Terra and GLM 5.3 open-weight models?

GPT-5.6 Terra: No linked weights. GLM 5.3: Restricted license. 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 GPT-5.6 Terra and GLM 5.3?

ModelCap currently lists 3 API providers for GPT-5.6 Terra and 32 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 GPT-5.6 Terra vs GLM 5.3 comparison?

Every figure and ModelCap Index position comes from the same published snapshot dated 2 October 2026. Publication and page updates happen separately; use the snapshot date shown on the page.

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