Model Comparison
GPT-5.6 Terra vs Grok 4.5Which is better in 2026?
GPT-5.6 Terra shows notably better performance in the majority of benchmarks. Grok 4.5 is 1.9x cheaper per token.
Verdict: GPT-5.6 Terra vs Grok 4.5 — which is better?
GPT-5.6 Terra (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-5.6 Terra outperforms in 5 benchmarks (Artificial Analysis, Artificial Analysis Coding Agent Index v1.1, DeepSWE, GDPval-AA, Terminal-Bench 2.1), while Grok 4.5 is better at 2 benchmarks (GPQA, SWE-Bench Pro). GPT-5.6 Terra shows notably better performance in the majority of benchmarks.
On price, Grok 4.5 is roughly 1.9x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.6 Terra 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 Terra if…
- you want the strongest raw capability — it leads on 5 of 7 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 Grok 4.5 if…
- cost matters — it's about 1.9x cheaper per token
Performance Benchmarks
Comparative analysis across standard metrics
GPT-5.6 Terra outperforms in 5 benchmarks (Artificial Analysis, Artificial Analysis Coding Agent Index v1.1, DeepSWE, GDPval-AA, Terminal-Bench 2.1), while Grok 4.5 is better at 2 benchmarks (GPQA, SWE-Bench Pro).
GPT-5.6 Terra shows notably better performance in the majority of benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, GPT-5.6 Terra ($2.50/1M tokens) is 1.3x more expensive than Grok 4.5 ($2.00/1M tokens).
For output processing, GPT-5.6 Terra ($15.00/1M tokens) is 2.5x more expensive than Grok 4.5 ($6.00/1M tokens).
In conclusion, GPT-5.6 Terra is more expensive than Grok 4.5.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-5.6 Terra accepts 1,050,000 input tokens compared to Grok 4.5's 500,000 tokens. Only GPT-5.6 Terra specifies output context (128,000 tokens).
Input Capabilities
Supported data types and modalities
Both GPT-5.6 Terra and Grok 4.5 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.6 Terra
Grok 4.5
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
GPT-5.6 Terra was released on 2026-07-09, while Grok 4.5 was released on 2026-07-08.
GPT-5.6 Terra is 0 month newer than Grok 4.5.
Jul 9, 2026
1 weeks ago
1d newerJul 8, 2026
1 weeks ago
Knowledge Cutoff
When training data ends
GPT-5.6 Terra has a documented knowledge cutoff of 2026-02-16, while Grok 4.5's cutoff date is not specified.
We can confirm GPT-5.6 Terra's training data extends to 2026-02-16, but cannot make a direct comparison without Grok 4.5's cutoff date.
Feb 2026
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Provider Availability
GPT-5.6 Terra is available from OpenAI. Grok 4.5 is available from xAI.
GPT-5.6 Terra
Grok 4.5
Outputs Comparison
Key Takeaways
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT-5.6 Terra and Grok 4.5 side-by-side, then vote on the output you prefer.
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FAQ
Common questions about GPT-5.6 Terra vs Grok 4.5.