OpenAI
GPT-5.6 Luna
Cost-efficient GPT-5.6 model for fast, high-volume workloads
- Context
- 1.1M
- Max output
- 128K
- Input / 1M
- $0.20
- Output / 1M
- $1.20
- Output speed
- —
Accepts
- Text input
- Image input
- PDF input
Produces
- Text output
AI model comparison
Compare recorded price, context, output limits, speed, latency, capabilities, and input/output support. Every missing value stays visible, and unsourced benchmarks are excluded.
GPT-5.6 Luna and Fugu Ultra both come up when teams are choosing a model for production work, and the honest answer usually depends on your workload rather than a leaderboard. This page puts their published specifications side by side — context window, token pricing, supported inputs and outputs — so you can see where they actually differ.
OpenAI
Cost-efficient GPT-5.6 model for fast, high-volume workloads
Accepts
Produces
Sakana AI
Quality-first multi-agent model for hard research, analysis, and competitions
Accepts
Produces
At a glance
This is a directional summary of the values recorded in this directory—not a universal quality verdict. Test the finalists on your own prompts before committing.
Where GPT-5.6 Luna leads in recorded data
Where Fugu Ultra leads in recorded data
Context capacity
Higher listed limit
GPT-5.6 Luna:1.1M
Fugu Ultra:1M
GPT-5.6 Luna
Maximum output
Higher listed limit
GPT-5.6 Luna:128K
Fugu Ultra:1M
Fugu Ultra
Input price
Lower recorded price
GPT-5.6 Luna:$0.20
Fugu Ultra:$5.00
GPT-5.6 Luna
Output price
Lower recorded price
GPT-5.6 Luna:$1.20
Fugu Ultra:$30.00
GPT-5.6 Luna
Output speed
Higher recorded throughput
GPT-5.6 Luna:—
Fugu Ultra:—
No complete comparison
Time to first token
Lower recorded latency
GPT-5.6 Luna:—
Fugu Ultra:—
No complete comparison
Intelligence Index
Higher directory index
GPT-5.6 Luna:—
Fugu Ultra:—
No complete comparison
Evidence
A score appears only when both records include a verified source. It is not treated as a universal ranking.
Specifications
| Specification | GPT-5.6 Luna | Fugu Ultra |
|---|---|---|
| Provider | OpenAI | Sakana AI |
| Model family | gpt-luna | fugu |
| Accepted inputs | text, image, pdf | text, image |
| Produced outputs | text | text |
| Context window | 1.1MRecorded lead | 1M |
| Max output | 128K | 1MRecorded lead |
| Intelligence Index | — | — |
| Input price / 1M | $0.20Recorded lead | $5.00 |
| Output price / 1M | $1.20Recorded lead | $30.00 |
| Output speed | — | — |
| Time to first token | — | — |
| 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 |
| Released | Jul 9, 2026 | Jun 15, 2026 |
Workload guidance
On the published numbers, GPT-5.6 Luna accepts the larger context window and GPT-5.6 Luna is cheaper per input token. Which matters more depends on whether your bottleneck is document size or spend — the table above has the exact figures.
Provenance
Prices and hosted performance can change. SyncDev records source references and clearly separates documented specifications from measured values; confirm commercial terms with the provider before deployment.
GPT-5.6 Luna
OpenAI · model record and recorded source
Fugu Ultra
Sakana AI · model record and recorded source
Choose any two approved model records and review them with the same evidence rules.