Question 1

What does this Kimi K3 vs GPT-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: Kimi K3 or GPT-5.1?

Accepted Answer

Kimi K3 lists $3.00 input and $15.00 output per 1M tokens. GPT-5.1 lists $1.25 input and $10.00 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: Kimi K3 or GPT-5.1?

Accepted Answer

Kimi K3 lists 1.05M tokens and GPT-5.1 lists 400K. Kimi K3 therefore has the larger recorded context window, but capacity alone is not a quality score.

Question 4

Which is faster: Kimi K3 or GPT-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 Kimi K3 and GPT-5.1 support?

Accepted Answer

Kimi K3 records text, image, video input and text output. GPT-5.1 records text, image 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 Kimi K3 or GPT-5.1?

Accepted Answer

Consider Kimi K3 if you need larger context or larger maximum output. Consider GPT-5.1 if you need a lower listed input rate or a lower listed output rate. Kimi K3 offers downloadable weights; GPT-5.1 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	Kimi K3	GPT-5.1
Provider	Moonshot AI	OpenAI
Listed pricing route	Moonshot AI	OpenAI
Model family	kimi-k3	gpt
Accepted inputs	text, image, video	text, image
Produced outputs	text	text
Context window	1.05MHigher	400K
Max output	1.05MHigher	128K
Input price / 1M	$3.00	$1.25Lower
Output price / 1M	$15.00	$10.00Lower
Reasoning mode	Documented	Documented
Tool calling	Documented	Documented
Image input	Documented	Documented
Audio input	Not documented	Not documented
Structured output	Documented	Documented
License	Open weights	Proprietary

Kimi K3 vs GPT-5.1

Kimi K3

GPT-5.1

Key differences

Pricing, limits and capabilities

Which model should you choose?

Documentation and model profiles

Questions people ask

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