Question 1

What does this GPT-5.1 Chat vs o3-pro 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-5.1 Chat or o3-pro?

Accepted Answer

GPT-5.1 Chat lists $1.25 input and $10.00 output per 1M tokens. o3-pro lists $20.00 input and $80.00 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: GPT-5.1 Chat or o3-pro?

Accepted Answer

GPT-5.1 Chat lists 128K tokens and o3-pro lists 200K. o3-pro therefore has the larger recorded context window, but capacity alone is not a quality score.

Question 4

Which is faster: GPT-5.1 Chat or o3-pro?

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-5.1 Chat and o3-pro support?

Accepted Answer

GPT-5.1 Chat records text, image input and text output. o3-pro 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 GPT-5.1 Chat or o3-pro?

Accepted Answer

Consider GPT-5.1 Chat if you need a lower listed input rate or a lower listed output rate. Consider o3-pro if you need larger context or larger maximum output. 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-5.1 Chat	o3-pro
Provider	OpenAI	OpenAI
Listed pricing route	OpenAI	OpenAI
Model family	gpt-codex	o-pro
Accepted inputs	text, image	text, image
Produced outputs	text	text
Context window	128K	200KHigher
Max output	16.38K	100KHigher
Input price / 1M	$1.25Lower	$20.00
Output price / 1M	$10.00Lower	$80.00
Reasoning mode	Documented	Documented
Tool calling	Documented	Documented
Image input	Documented	Documented
Audio input	Not documented	Not documented
Structured output	Documented	Documented
License	Proprietary	Proprietary

GPT-5.1 Chat vs o3-pro

GPT-5.1 Chat

o3-pro

Key differences

Pricing, limits and capabilities

Which model should you choose?

Documentation and model profiles

Questions people ask

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