Model Comparison
GPT-5.6 Luna vs GPT OSS 120B HighWhich is better in 2026?
GPT-5.6 Luna significantly outperforms across most benchmarks. GPT OSS 120B High is 11.3x cheaper per token.
Verdict: GPT-5.6 Luna vs GPT OSS 120B High — which is better?
GPT-5.6 Luna (by OpenAI) and GPT OSS 120B High (by OpenAI) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
GPT-5.6 Luna outperforms in 1 benchmarks (GPQA), while GPT OSS 120B High is better at 0 benchmarks. GPT-5.6 Luna significantly outperforms across most benchmarks.
On price, GPT OSS 120B High is roughly 11.3x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.6 Luna also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose GPT-5.6 Luna if…
- you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
- you process long inputs — it offers a 1,050,000 token context window
- you want the most recent training data — it shipped Jul 2026
Choose GPT OSS 120B High if…
- cost matters — it's about 11.3x cheaper per token
- you need open weights you can self-host or fine-tune
Performance Benchmarks
Comparative analysis across standard metrics
GPT-5.6 Luna outperforms in 1 benchmarks (GPQA), while GPT OSS 120B High is better at 0 benchmarks.
GPT-5.6 Luna significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.6 Luna ($1.00/1M tokens) is 10.0x more expensive than GPT OSS 120B High ($0.10/1M tokens).
For output processing, GPT-5.6 Luna ($6.00/1M tokens) is 12.0x more expensive than GPT OSS 120B High ($0.50/1M tokens).
In conclusion, GPT-5.6 Luna is more expensive than GPT OSS 120B High.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-5.6 Luna accepts 1,050,000 input tokens compared to GPT OSS 120B High's 131,072 tokens. GPT OSS 120B High can generate longer responses up to 131,072 tokens, while GPT-5.6 Luna is limited to 128,000 tokens.
Input Capabilities
Supported data types and modalities
GPT-5.6 Luna supports multimodal inputs, whereas GPT OSS 120B High does not.
GPT-5.6 Luna can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT-5.6 Luna
GPT OSS 120B High
License
Usage and distribution terms
GPT-5.6 Luna is licensed under a proprietary license, while GPT OSS 120B High uses Apache 2.0.
License differences may affect how you can use these models in commercial or open-source projects.
Proprietary
Closed source
Apache 2.0
Open weights
Release Timeline
When each model was launched
GPT-5.6 Luna was released on 2026-07-09, while GPT OSS 120B High was released on 2025-08-05.
GPT-5.6 Luna is 11 months newer than GPT OSS 120B High.
Jul 9, 2026
1 weeks ago
11mo newerAug 5, 2025
11 months ago
Knowledge Cutoff
When training data ends
GPT-5.6 Luna has a documented knowledge cutoff of 2026-02-16, while GPT OSS 120B High's cutoff date is not specified.
We can confirm GPT-5.6 Luna's training data extends to 2026-02-16, but cannot make a direct comparison without GPT OSS 120B High's cutoff date.
Feb 2026
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Provider Availability
GPT-5.6 Luna is available from OpenAI. GPT OSS 120B High is available from OpenAI, Fireworks.
GPT-5.6 Luna
GPT OSS 120B High
Outputs Comparison
Key Takeaways
GPT-5.6 Luna
View detailsOpenAI
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT-5.6 Luna and GPT OSS 120B High side-by-side, then vote on the output you prefer.
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FAQ
Common questions about GPT-5.6 Luna vs GPT OSS 120B High.