Question 1

What does this GPT-5.6 Terra vs GLM-5.1 comparison cover?

Accepted Answer

It brings together documented inputs and outputs, token limits, deployment terms and available pricing. When both models have source-linked, verified results on a shared benchmark, those results are shown with their individual sources. The comparison is a starting point for evaluating your own workload.

Question 2

Which is cheaper: GPT-5.6 Terra or GLM-5.1?

Accepted Answer

GPT-5.6 Terra lists $2.00 input and $12.00 output per 1M tokens. GLM-5.1 lists $1.40 input and $4.40 output. The cheaper workload depends on the mix of input and output. Long-context tiers, caching, batch processing and retries can change the bill.

Question 3

Which has the larger context window: GPT-5.6 Terra or GLM-5.1?

Accepted Answer

GPT-5.6 Terra lists 1.05M tokens and GLM-5.1 lists 200K. GPT-5.6 Terra therefore has the larger recorded context window, but capacity alone is not a quality score.

Question 4

Which is faster: GPT-5.6 Terra or GLM-5.1?

Accepted Answer

There is no matched speed measurement for both models with the same source, host, region and date. Test the same prompts at your expected concurrency and measure time to the first useful response as well as complete task time.

Question 5

What input and output types do GPT-5.6 Terra and GLM-5.1 support?

Accepted Answer

GPT-5.6 Terra records text, image, pdf input and text output. GLM-5.1 records text input and text output. “Not documented” means the current source record is incomplete; it does not prove that a modality is unsupported.

Question 6

Should I choose GPT-5.6 Terra or GLM-5.1?

Accepted Answer

Consider GPT-5.6 Terra if you need larger context. Consider GLM-5.1 if you need larger maximum output or a lower listed input rate or a lower listed output rate. GLM-5.1 offers downloadable weights; GPT-5.6 Terra is listed as a proprietary model. Compare licence terms and operating costs before choosing a deployment. Test both on the same representative examples and judge the output against your acceptance criteria. Include tool failures, retries and the time to a completed task.

Specification	GPT-5.6 Terra	GLM-5.1
Provider	OpenAI	Z.ai / Zhipu AI
Listed pricing route	OpenAI	Z.ai / Zhipu AI
Model family	gpt-terra	glm
Accepted inputs	text, image, pdf	text
Produced outputs	text	text
Context window	1.05MHigher	200K
Max output	128K	131.07KHigher
Input price / 1M	$2.00	$1.40Lower
Output price / 1M	$12.00	$4.40Lower
Reasoning mode	Documented	Documented
Tool calling	Documented	Documented
Image input	Documented	Not documented
Audio input	Not documented	Not documented
Structured output	Documented	Documented
License	Proprietary	Open weights

GPT-5.6 Terra vs GLM-5.1

GPT-5.6 Terra

GLM-5.1

Key differences

Pricing, limits and capabilities

Which model should you choose?

Documentation and model profiles

Questions people ask

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