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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 19 August 2026

As of 19 August 2026, GLM 5.3 holds the stronger ModelCap Index position (#7 vs #12); 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…

  • you want provider choice — 3 listed API providers against 1.

Choose GLM 5.3 if…

  • you want the stronger overall ModelCap Index position — #7 against #12 (78.4 vs 73.8 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.
  • Artificial Analysis Intelligence Index is your yardstick — 59.5 against 56.6.
  • 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#12#7
Index score73.878.4
EvidenceMeasuredMeasured
Input price / 1M tokens$2.00$1.40
Output price / 1M tokens$12.00$4.40
Context window1M tokens1M tokens
Max output tokens128K131K
API providers listed31
Weight accessAPI onlyAPI only
Input modalitiesFile, Image, TextText
First listed9 July 202618 August 2026
PublisherOpenAIZ.ai

Evidence: 6 public benchmark observations across 6 boards · 1 public benchmark observation across 1 board. 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 codingArena (LMArena)15161506–1525X-High—Only one result
LMArena AgentLMArena3.8%2.5%–5.0%X-High—Only one result
ARC-AGI-2ARC Prize Foundation83.9%Max—Only one result
ARC-AGI-3ARC Prize Foundation0.8%Max—Only one result
Artificial Analysis Intelligence IndexArtificial Analysis56.6intelligence-index59.5intelligence-indexGLM 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 19 August 2026: #7 against #12. 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.

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.

Which has the bigger context window, GPT-5.6 Terra or GLM 5.3?

Both publish a 1M-token context window.

Which is better for coding, GPT-5.6 Terra or GLM 5.3?

The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.

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

GPT-5.6 Terra: API only. GLM 5.3: API only. 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 GPT-5.6 Terra and GLM 5.3?

ModelCap currently lists 3 API providers for GPT-5.6 Terra and 1 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 comes from the sealed ModelCap dataset published 19 August 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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