Model Comparison

GPT OSS 120B vs Grok 4.5Which is better in 2026?

Grok 4.5 significantly outperforms across most benchmarks. GPT OSS 120B is 16.7x cheaper per token.

Verdict: GPT OSS 120B vs Grok 4.5 — which is better?

GPT OSS 120B (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 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 is roughly 16.7x 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 if…

  • cost matters — it's about 16.7x 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

1 benchmarks

GPT OSS 120B outperforms in 0 benchmarks, while Grok 4.5 is better at 1 benchmark (GPQA).

Grok 4.5 significantly outperforms across most benchmarks.

Fri Jul 24 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

GPT OSS 120B costs less

For input processing, GPT OSS 120B ($0.09/1M tokens) is 22.2x cheaper than Grok 4.5 ($2.00/1M tokens).

For output processing, GPT OSS 120B ($0.45/1M tokens) is 13.3x cheaper than Grok 4.5 ($6.00/1M tokens).

In conclusion, Grok 4.5 is more expensive than GPT OSS 120B.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Fri Jul 24 2026 • llm-stats.com
OpenAI
GPT OSS 120B
Input tokens$0.09
Output tokens$0.45
Best providerDeepinfra
xAI
Grok 4.5
Input tokens$2.00
Output tokens$6.00
Best providerxAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Grok 4.5 accepts 500,000 input tokens compared to GPT OSS 120B's 131,072 tokens. Only GPT OSS 120B specifies output context (131,072 tokens).

OpenAI
GPT OSS 120B
Input131,072 tokens
Output131,072 tokens
xAI
Grok 4.5
Input500,000 tokens
Output- tokens
Fri Jul 24 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Grok 4.5 supports multimodal inputs, whereas GPT OSS 120B 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

Text
Images
Audio
Video

Grok 4.5

Text
Images
Audio
Video

License

Usage and distribution terms

GPT OSS 120B 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.

GPT OSS 120B

Apache 2.0

Open weights

Grok 4.5

Proprietary

Closed source

Release Timeline

When each model was launched

GPT OSS 120B 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.

GPT OSS 120B

Aug 5, 2025

11 months ago

Grok 4.5

Jul 16, 2026

1 weeks ago

11mo newer

Knowledge Cutoff

When training data ends

Grok 4.5 has a documented knowledge cutoff of 2026-02-01, while GPT OSS 120B'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's cutoff date.

GPT OSS 120B

—

Grok 4.5

Feb 2026

Provider Availability

GPT OSS 120B is available from DeepInfra, Novita, OpenAI, Fireworks, Groq. Grok 4.5 is available from xAI.

GPT OSS 120B

deepinfra logo
Deepinfra
Input Price:Input: $0.09/1MOutput Price:Output: $0.45/1M
novita logo
Novita
Input Price:Input: $0.10/1MOutput Price:Output: $0.50/1M
openai logo
OpenAI
Input Price:Input: $0.10/1MOutput Price:Output: $0.50/1M
fireworks logo
Fireworks
Input Price:Input: $0.15/1MOutput Price:Output: $0.60/1M
groq logo
Groq
Input Price:Input: $0.15/1MOutput Price:Output: $0.60/1M

Grok 4.5

xai logo
xAI
Input Price:Input: $2.00/1MOutput Price:Output: $6.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

OpenAI
Less expensive input tokens
Less expensive output tokens
Has open weights
xAI
Larger context window (500,000 tokens)
Supports multimodal inputs
Higher GPQA score (93.0% vs 80.1%)

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against GPT OSS 120B and Grok 4.5 side-by-side, then vote on the output you prefer.

GPT OSS 120B
✓ Preferred
Grok 4.5
Open in Playground
AI Model Comparison Table
Feature
OpenAI
GPT OSS 120B
xAI
Grok 4.5

FAQ

Common questions about GPT OSS 120B vs Grok 4.5.

Which is better, GPT OSS 120B or Grok 4.5?

Grok 4.5 significantly outperforms across most benchmarks. GPT OSS 120B is made by OpenAI and Grok 4.5 is made by xAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does GPT OSS 120B compare to Grok 4.5 in benchmarks?

GPT OSS 120B scores MMLU: 90.0%, CodeForces: 82.1%, GPQA: 80.1%, TAU-bench Retail: 67.8%, HealthBench: 57.6%. Grok 4.5 scores GPQA: 93.0%, Terminal-Bench 2.1: 83.3%, Artificial Analysis Coding Agent Index v1.1: 76.0%, SWE-Bench Pro: 64.7%, AA-Omniscience Index: 63.0%.

Is GPT OSS 120B cheaper than Grok 4.5?

GPT OSS 120B is 22.2x cheaper for input tokens. GPT OSS 120B costs $0.09/M input and $0.45/M output via deepinfra. Grok 4.5 costs $2.00/M input and $6.00/M output via xai.

What are the context window sizes for GPT OSS 120B and Grok 4.5?

GPT OSS 120B supports 131K tokens and Grok 4.5 supports 500K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT OSS 120B and Grok 4.5?

Key differences include context window (131K vs 500K), input pricing ($0.09 vs $2.00/M), multimodal support (no vs yes), licensing (Apache 2.0 vs Proprietary). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT OSS 120B and Grok 4.5?

GPT OSS 120B is developed by OpenAI and Grok 4.5 is developed by xAI.

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