Fugu Ultra vs GPT-5.5 Instant
Fugu Ultra (2026) and GPT-5.5 Instant (2026) are frontier reasoning models from Sakana AI and OpenAI. Fugu Ultra ships a 1m-token context window, while GPT-5.5 Instant ships a 400k-token context window. On pricing, Fugu Ultra ranges from $5 to $10/1M input tokens by tier; GPT-5.5 Instant costs $5/1M input tokens. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Fugu Ultra is safer overall; choose GPT-5.5 Instant when coding workflow support matters.
Decision scorecard
Local evidence first| Signal | Fugu Ultra | GPT-5.5 Instant |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | multimodal apps and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 400k |
| Cheapest output | $30/1M tokens | $30/1M tokens |
| Provider routes | 2 tracked | 1 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Fugu Ultra has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Fugu Ultra has broader tracked provider coverage for fallback and procurement flexibility.
- Fugu Ultra uniquely exposes Reasoning in local model data.
- Local decision data tags Fugu Ultra for Coding, RAG, and Agents.
- GPT-5.5 Instant uniquely exposes Code execution in local model data.
- Local decision data tags GPT-5.5 Instant for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Fugu Ultra
$11,500
Cheapest tracked route/tier: Sakana AI <=272K tokens
GPT-5.5 Instant
$11,500
Cheapest tracked route/tier: OpenAI API
Estimated monthly gap: $0.00. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Fugu Ultra and GPT-5.5 Instant; plan for SDK, billing, or endpoint changes.
- Cheapest tracked output pricing is tied, so migration risk shifts to quality, latency, and provider packaging.
- Check replacement coverage for Reasoning before moving production traffic.
- GPT-5.5 Instant adds Code execution in local capability data.
- No overlapping tracked provider route is sourced for GPT-5.5 Instant and Fugu Ultra; plan for SDK, billing, or endpoint changes.
- Cheapest tracked output pricing is tied, so migration risk shifts to quality, latency, and provider packaging.
- Check replacement coverage for Code execution before moving production traffic.
- Fugu Ultra adds Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-06-22 | 2026-05-05 |
| Context window | 1m | 400k |
| Parameters | — | — |
| Architecture | Composition of Experts | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | - | 2025-08 |
Pricing and availability
| Pricing attribute | Fugu Ultra | GPT-5.5 Instant |
|---|---|---|
| Input price |
| $5/1M tokens |
| Output price |
| $30/1M tokens |
| Providers |
Capabilities
| Capability | Fugu Ultra | GPT-5.5 Instant |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | No |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
Deep dive
The capability footprint differs most on reasoning mode: Fugu Ultra and code execution: GPT-5.5 Instant. Both models share vision, multimodal input, function calling, and tool use, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Fugu Ultra lists tiered pricing: <=272K tokens is $5/1M input and $30/1M output; >272K tokens is $10/1M input and $45/1M output, while GPT-5.5 Instant lists $5/1M input and $30/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend is tied on the cheapest tracked routes. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 2 providers versus 1, so concentration risk also matters.
Choose Fugu Ultra when reasoning depth, larger context windows, and broader provider choice are central to the workload. Choose GPT-5.5 Instant when coding workflow support are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Fugu Ultra or GPT-5.5 Instant?
Fugu Ultra supports 1m tokens, while GPT-5.5 Instant supports 400k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Fugu Ultra or GPT-5.5 Instant?
Neither is cheaper on tracked token pricing. Both list $5/1M input and $30/1M output tokens on the cheapest tracked route. Provider discounts, batch pricing, or route-specific tiers can still change the final bill.
Is Fugu Ultra or GPT-5.5 Instant open source?
Fugu Ultra is listed under Proprietary. GPT-5.5 Instant is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Fugu Ultra or GPT-5.5 Instant?
Both Fugu Ultra and GPT-5.5 Instant expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Fugu Ultra or GPT-5.5 Instant?
Both Fugu Ultra and GPT-5.5 Instant expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Where can I run Fugu Ultra and GPT-5.5 Instant?
Fugu Ultra is available on Sakana AI and Vercel AI Gateway. GPT-5.5 Instant is available on OpenAI API. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-22. Data sourced from public model cards and provider documentation.