Question 1

What does this GPT-5.1 vs Fugu Ultra 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 or Fugu Ultra?

Accepted Answer

GPT-5.1 lists $1.25 input and $10.00 output per 1M tokens. Fugu Ultra lists $5.00 input and $30.00 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 or Fugu Ultra?

Accepted Answer

GPT-5.1 lists 400K tokens and Fugu Ultra lists 1M. Fugu Ultra therefore has the larger recorded context window, but capacity alone is not a quality score.

Question 4

Which is faster: GPT-5.1 or Fugu Ultra?

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 and Fugu Ultra support?

Accepted Answer

GPT-5.1 records text, image input and text output. Fugu Ultra 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 or Fugu Ultra?

Accepted Answer

Consider GPT-5.1 if you need a lower listed input rate or a lower listed output rate. Consider Fugu Ultra if you need larger context. 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	Fugu Ultra
Provider	OpenAI	Sakana AI
Listed pricing route	OpenAI	Sakana AI
Model family	gpt	fugu
Accepted inputs	text, image	text, image
Produced outputs	text	text
Context window	400K	1MHigher
Max output	128K	—
Input price / 1M	$1.25Lower	$5.00
Output price / 1M	$10.00Lower	$30.00
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 vs Fugu Ultra

GPT-5.1

Fugu Ultra

Key differences

Pricing, limits and capabilities

Which model should you choose?

Documentation and model profiles

Questions people ask

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