API cost decision in 10 seconds

Claude Opus 5 (Fast) vs Fugu Ultra

Pick Fugu Ultra when budget is the priority.

Page updated: 2026-07-24T18:08:02Z Data confirmed: 2026-08-23T12:07:48Z Prices normalized to USD per 1M tokens Sample workload: 1M input + 500K output

Budget verdict

Pick Fugu Ultra when budget is the priority.

On the standard 1M input plus 500K output workload, Fugu Ultra is estimated at $20 vs $35 for Claude Opus 5 (Fast), saving $15 (42.9% lower).

Cost-first pickFugu Ultra

Context-first pickBoth models

Sample savings$1542.9%

10x traffic gap$150

The reported context window is tied, so cost and provider fit carry more weight. At 10x that traffic, the same price gap is about $150. Use the calculator below to replace the sample workload with your own token volume.

Cost sensitivity

Workload Sensitivity

Same prices, different token mixes.

Fugu Ultra stays cheaper across input-heavy, balanced, and output-heavy sample workloads.

Workload shape	Token mix	Better pick	Claude Opus 5 (Fast)	Fugu Ultra
Input-heavy / RAG	5M input + 500K output	Fugu Ultra	$75	$40
Balanced workload	1M input + 1M output	Fugu Ultra	$60	$35
Output-heavy chatbot	1M input + 5M output	Fugu Ultra	$260	$155

Cheaper input Fugu Ultra $10 vs $5 / 1M

Fugu Ultra is $5 cheaper per 1M input tokens (50% lower; 2x difference).

Cheaper output Fugu Ultra $50 vs $30 / 1M

Fugu Ultra is $20 cheaper per 1M output tokens (40% lower; 1.67x difference).

Larger context Tie 1M vs 1M

Both models report the same context window at 1M tokens.

Sample workload Fugu Ultra $35 vs $20

Fugu Ultra is $15 cheaper on the standard workload (42.9% lower).

Estimate your workload cost

Your Workload Cost

Prices are normalized to USD per 1M tokens.

Monthly input tokens Monthly output tokens

Claude Opus 5 (Fast) Calculating… Estimated API cost

Fugu Ultra Calculating… Estimated API cost

Cheaper for this workload Calculating… Difference: calculating…

This estimate uses normalized public API pricing per 1M tokens. It is a planning aid, not a billing quote. Verify provider pricing, limits, and terms before production use.

Quick Decision

Verdict

Fugu Ultra has the lower input price; Fugu Ultra has the lower output price; both models report the same context window. For the 1M input plus 500K output sample, Fugu Ultra is cheaper for the standard workload.

For a 1M input token plus 500K output token workload, the estimated API cost is $35 for Claude Opus 5 (Fast) and $20 for Fugu Ultra.

Best Fit

Choose Claude Opus 5 (Fast) when its provider, model quality, latency, or availability is more important than the numeric price/context winner.

Choose Fugu Ultra when you care most about lower input-token price, and lower output-token price.

Decision Notes

On the standard 1M input plus 500K output workload, Fugu Ultra is estimated at $20 vs $35 for Claude Opus 5 (Fast), saving $15 (42.9% lower).
Fugu Ultra is $15 cheaper on the standard workload (42.9% lower).
Fugu Ultra is $5 cheaper per 1M input tokens (50% lower; 2x difference).
Fugu Ultra is $20 cheaper per 1M output tokens (40% lower; 1.67x difference).
Both models report the same context window at 1M tokens.

Head-to-Head Specs

Feature	Claude Opus 5 (Fast) (Anthropic)	Fugu Ultra (Sakana)
Input Price prompt tokens per 1M	$10	$5
Completion Price per 1M tokens	$50	$30
Sample Workload Cost 1M input + 500K output	$35	$20
Context Window	1M	1M
Release Date	2026-07-24	2026-06-24

Use-Case Decision Matrix

Use case	Better pick	Why
Budget-constrained production	Fugu Ultra	On the standard 1M input plus 500K output workload, Fugu Ultra is estimated at $20 vs $35 for Claude Opus 5 (Fast), saving $15 (42.9% lower).
High-volume input processing	Fugu Ultra	Lower prompt-token price matters most when prompts, retrieved passages, or documents dominate the bill.
Long responses and chatbots	Fugu Ultra	Lower output-token price matters most when assistants generate many completion tokens.
RAG or long-document work	Tie	A larger context window leaves more room for retrieved passages, conversation history, or source files.

Related Alternatives

Same-provider lower-cost swaps

Claude 3 Haiku can replace Claude Opus 5 (Fast) when lower sample workload cost matters most: $0.88.
Claude Haiku 4.5 (batch) can replace Claude Opus 5 (Fast) when lower sample workload cost matters most: $1.75.
Claude 3.5 Haiku can replace Claude Opus 5 (Fast) when lower sample workload cost matters most: $2.8.
Claude Sonnet 5 (batch) can replace Claude Opus 5 (Fast) when lower sample workload cost matters most: $3.5.

Larger context near this budget

Grok 4.20 Multi-Agent offers 2M context with $2.5 sample workload cost.
Grok 4.20 offers 2M context with $2.5 sample workload cost.
DeepSeek V4 Flash 0731 offers 1.31M context with $0.17 sample workload cost.
DeepSeek V4 Flash Latest offers 1.31M context with $0.11 sample workload cost.

Popular competitors

DeepSeek V4 Flash 0731 · DeepSeek · #1
MiMo-V2.5 · Xiaomi · #2
Hy3 · Tencent · #3
Ox Alpha · stealth · #4

Cheaper alternatives

Review low-cost models sorted by a standard 1M input plus 500K output workload.

Open cheapest models

Larger context alternatives

Find models with larger context windows for RAG, long documents, and codebase review.

Open largest context models

Provider catalogs

Compare models within provider hubs before choosing a final API vendor.

Open provider hubs

Anthropic catalog

Review all tracked Anthropic models before deciding whether this matchup is the right shortlist.

Open Anthropic models

Sakana catalog

Check other Sakana models with comparable pricing, context, or release timing.

Open Sakana models

Claude Opus 5 (Fast)

Fast-mode variant of [Opus 5](/anthropic/claude-opus-5) - identical capabilities with higher output speed at 2x pricing relative to regular Opus 5. Learn more in Anthropic's docs: https://platform.claude.com/docs/en/build-with-claude/fast-mode

Fugu Ultra

Fugu Ultra is the higher-performance model in Sakana AI's Fugu family. Rather than a single monolithic model, Fugu is a learned multi-agent orchestration system: a language model trained to route...