Model Comparison
GPT OSS 120B High vs Grok 4.5Which is better in 2026?
Grok 4.5 significantly outperforms across most benchmarks. GPT OSS 120B High is 15.0x cheaper per token.
Verdict: GPT OSS 120B High vs Grok 4.5 — which is better?
GPT OSS 120B High (by OpenAI) and Grok 4.5 (by xAI) 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 OSS 120B High outperforms in 0 benchmarks, while Grok 4.5 is better at 1 benchmark (GPQA). Grok 4.5 significantly outperforms across most benchmarks.
On price, GPT OSS 120B High is roughly 15.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Grok 4.5 also accepts a larger context window (500,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose GPT OSS 120B High if…
- cost matters — it's about 15.0x cheaper per token
- you need open weights you can self-host or fine-tune
Choose Grok 4.5 if…
- you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
- you process long inputs — it offers a 500,000 token context window
- you want the most recent training data — it shipped Jul 2026
Performance Benchmarks
Comparative analysis across standard metrics
GPT OSS 120B High outperforms in 0 benchmarks, while Grok 4.5 is better at 1 benchmark (GPQA).
Grok 4.5 significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, GPT OSS 120B High ($0.10/1M tokens) is 20.0x cheaper than Grok 4.5 ($2.00/1M tokens).
For output processing, GPT OSS 120B High ($0.50/1M tokens) is 12.0x cheaper than Grok 4.5 ($6.00/1M tokens).
In conclusion, Grok 4.5 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
Grok 4.5 accepts 500,000 input tokens compared to GPT OSS 120B High's 131,072 tokens. Only GPT OSS 120B High specifies output context (131,072 tokens).
Input Capabilities
Supported data types and modalities
Grok 4.5 supports multimodal inputs, whereas GPT OSS 120B High does not.
Grok 4.5 can handle both text and other forms of data like images, making it suitable for multimodal applications.
GPT OSS 120B High
Grok 4.5
License
Usage and distribution terms
GPT OSS 120B High is licensed under Apache 2.0, while Grok 4.5 uses a proprietary license.
License differences may affect how you can use these models in commercial or open-source projects.
Apache 2.0
Open weights
Proprietary
Closed source
Release Timeline
When each model was launched
GPT OSS 120B High was released on 2025-08-05, while Grok 4.5 was released on 2026-07-16.
Grok 4.5 is 12 months newer than GPT OSS 120B High.
Aug 5, 2025
11 months ago
Jul 16, 2026
4 days ago
11mo newerKnowledge Cutoff
When training data ends
Grok 4.5 has a documented knowledge cutoff of 2026-02-01, while GPT OSS 120B High's cutoff date is not specified.
We can confirm Grok 4.5's training data extends to 2026-02-01, but cannot make a direct comparison without GPT OSS 120B High's cutoff date.
—
Feb 2026
Provider Availability
GPT OSS 120B High is available from OpenAI, Fireworks. Grok 4.5 is available from xAI.
GPT OSS 120B High
Grok 4.5
Outputs Comparison
Key Takeaways
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT OSS 120B High and Grok 4.5 side-by-side, then vote on the output you prefer.
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FAQ
Common questions about GPT OSS 120B High vs Grok 4.5.