Model Comparison
GPT-5.5 vs Grok 4.5Which is better in 2026?
Grok 4.5 shows notably better performance in the majority of benchmarks. Grok 4.5 is 3.8x cheaper per token.
Verdict: GPT-5.5 vs Grok 4.5 — which is better?
GPT-5.5 (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-5.5 outperforms in 1 benchmarks (GPQA), while Grok 4.5 is better at 2 benchmarks (GDPval-AA, SWE-Bench Pro). Grok 4.5 shows notably better performance in the majority of benchmarks.
On price, Grok 4.5 is roughly 3.8x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-5.5 also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.
Choose GPT-5.5 if…
- you process long inputs — it offers a 1,050,000 token context window
Choose Grok 4.5 if…
- you want the strongest raw capability — it leads on 2 of 3 shared benchmarks
- cost matters — it's about 3.8x cheaper per token
- you want the most recent training data — it shipped Jul 2026
Performance Benchmarks
Comparative analysis across standard metrics
GPT-5.5 outperforms in 1 benchmarks (GPQA), while Grok 4.5 is better at 2 benchmarks (GDPval-AA, SWE-Bench Pro).
Grok 4.5 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-5.5 ($5.00/1M tokens) is 2.5x more expensive than Grok 4.5 ($2.00/1M tokens).
For output processing, GPT-5.5 ($30.00/1M tokens) is 5.0x more expensive than Grok 4.5 ($6.00/1M tokens).
In conclusion, GPT-5.5 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-5.5 accepts 1,050,000 input tokens compared to Grok 4.5's 500,000 tokens. Only GPT-5.5 specifies output context (128,000 tokens).
Input Capabilities
Supported data types and modalities
Both GPT-5.5 and Grok 4.5 support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.5
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-5.5 was released on 2026-04-23, while Grok 4.5 was released on 2026-07-08.
Grok 4.5 is 3 months newer than GPT-5.5.
Apr 23, 2026
2 months ago
Jul 8, 2026
1 weeks ago
2mo newerKnowledge Cutoff
When training data ends
GPT-5.5 has a documented knowledge cutoff of 2025-12-01, while Grok 4.5's cutoff date is not specified.
We can confirm GPT-5.5's training data extends to 2025-12-01, but cannot make a direct comparison without Grok 4.5's cutoff date.
Dec 2025
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Provider Availability
GPT-5.5 is available from OpenAI. Grok 4.5 is available from xAI.
GPT-5.5
Grok 4.5
Outputs Comparison
Key Takeaways
GPT-5.5
View detailsOpenAI
Detailed Comparison
Interactive Arena
Judge for yourself.
Run your own prompts against GPT-5.5 and Grok 4.5 side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.5 vs Grok 4.5.