Question 1

What does this GPT-5.1 Codex vs o1-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 Codex or o1-pro?

Accepted Answer

GPT-5.1 Codex lists $1.25 input and $10.00 output per 1M tokens. o1-pro lists $150.00 input and $600.00 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 Codex or o1-pro?

Accepted Answer

GPT-5.1 Codex lists 400K tokens and o1-pro lists 200K. GPT-5.1 Codex therefore has the larger recorded context window, but capacity alone is not a quality score.

Question 4

Which is faster: GPT-5.1 Codex or o1-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 Codex and o1-pro support?

Accepted Answer

GPT-5.1 Codex records text, image input and text output. o1-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 Codex or o1-pro?

Accepted Answer

Consider GPT-5.1 Codex if you need larger context or larger maximum output or a lower listed input rate or a lower listed output rate. 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 Codex	o1-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	400KHigher	200K
Max output	128KHigher	100K
Input price / 1M	$1.25Lower	$150.00
Output price / 1M	$10.00Lower	$600.00
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 Codex vs o1-pro

GPT-5.1 Codex

o1-pro

Key differences

Pricing, limits and capabilities

Which model should you choose?

Documentation and model profiles

Questions people ask

Compare a different pair