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.
Claude Sonnet 4.5 (latest) and GPT-5.6 Luna 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.
Anthropic
Balanced Claude model for coding, analysis, agent workflows, and cost control
Accepts
Produces
OpenAI
Cost-efficient GPT-5.6 model for fast, high-volume workloads
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 Claude Sonnet 4.5 (latest) leads in recorded data
No complete recorded factor currently favors this model. That does not establish lower real-world quality.
Where GPT-5.6 Luna leads in recorded data
Context capacity
Higher listed limit
Claude Sonnet 4.5 (latest):200K
GPT-5.6 Luna:1.1M
GPT-5.6 Luna
Maximum output
Higher listed limit
Claude Sonnet 4.5 (latest):64K
GPT-5.6 Luna:128K
GPT-5.6 Luna
Input price
Lower recorded price
Claude Sonnet 4.5 (latest):$3.00
GPT-5.6 Luna:$0.20
GPT-5.6 Luna
Output price
Lower recorded price
Claude Sonnet 4.5 (latest):$15.00
GPT-5.6 Luna:$1.20
GPT-5.6 Luna
Output speed
Higher recorded throughput
Claude Sonnet 4.5 (latest):—
GPT-5.6 Luna:—
No complete comparison
Time to first token
Lower recorded latency
Claude Sonnet 4.5 (latest):—
GPT-5.6 Luna:—
No complete comparison
Intelligence Index
Higher directory index
Claude Sonnet 4.5 (latest):—
GPT-5.6 Luna:—
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 | Claude Sonnet 4.5 (latest) | GPT-5.6 Luna |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Model family | claude-sonnet | gpt-luna |
| Accepted inputs | text, image, pdf | text, image, pdf |
| Produced outputs | text | text |
| Context window | 200K | 1.1MRecorded lead |
| Max output | 64K | 128KRecorded lead |
| Intelligence Index | — | — |
| Input price / 1M | $3.00 | $0.20Recorded lead |
| Output price / 1M | $15.00 | $1.20Recorded lead |
| 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 | Not documented | Documented |
| License | Proprietary | Proprietary |
| Released | Sep 29, 2025 | Jul 9, 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.
Claude Sonnet 4.5 (latest)
Anthropic · model record and recorded source
GPT-5.6 Luna
OpenAI · model record and recorded source
Choose any two approved model records and review them with the same evidence rules.