Question 1

What does this GPT-5.1 Codex Max vs o4-mini 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 Max or o4-mini?

Accepted Answer

GPT-5.1 Codex Max lists $1.25 input and $10.00 output per 1M tokens. o4-mini lists $1.10 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-5.1 Codex Max or o4-mini?

Accepted Answer

GPT-5.1 Codex Max lists 400K tokens and o4-mini lists 200K. GPT-5.1 Codex Max therefore has the larger recorded context window, but capacity alone is not a quality score.

Question 4

Which is faster: GPT-5.1 Codex Max or o4-mini?

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 Max and o4-mini support?

Accepted Answer

GPT-5.1 Codex Max records text, image input and text output. o4-mini 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 Max or o4-mini?

Accepted Answer

Consider GPT-5.1 Codex Max if you need larger context or larger maximum output. Consider o4-mini if you need 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 Max	o4-mini
Provider	OpenAI	OpenAI
Listed pricing route	OpenAI	OpenAI
Model family	gpt-codex	o-mini
Accepted inputs	text, image	text, image
Produced outputs	text	text
Context window	400KHigher	200K
Max output	128KHigher	100K
Input price / 1M	$1.25	$1.10Lower
Output price / 1M	$10.00	$4.40Lower
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 Max vs o4-mini

GPT-5.1 Codex Max

o4-mini

Key differences

Pricing, limits and capabilities

Which model should you choose?

Documentation and model profiles

Questions people ask

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