Model Comparison

GPT-5.5 Pro vs Grok 4.5Which is better in 2026?

Comparing GPT-5.5 Pro and Grok 4.5 across benchmarks, pricing, and capabilities.

Verdict: GPT-5.5 Pro vs Grok 4.5 — which is better?

GPT-5.5 Pro (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.

On price, Grok 4.5 is roughly 22.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

GPT-5.5 Pro 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 Pro if…

  • you process long inputs — it offers a 1,050,000 token context window

Choose Grok 4.5 if…

  • cost matters — it's about 22.5x cheaper per token
  • you want the most recent training data — it shipped Jul 2026

Performance Benchmarks

Comparative analysis across standard metrics

No common benchmarks found

GPT-5.5 Pro and Grok 4.5don't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

Grok 4.5 costs less

For input processing, GPT-5.5 Pro ($30.00/1M tokens) is 15.0x more expensive than Grok 4.5 ($2.00/1M tokens).

For output processing, GPT-5.5 Pro ($180.00/1M tokens) is 30.0x more expensive than Grok 4.5 ($6.00/1M tokens).

In conclusion, GPT-5.5 Pro is more expensive than Grok 4.5.*

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

Lowest available price from all providers
Fri Jul 17 2026 • llm-stats.com
OpenAI
GPT-5.5 Pro
Input tokens$30.00
Output tokens$180.00
Best providerOpenAI
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

GPT-5.5 Pro accepts 1,050,000 input tokens compared to Grok 4.5's 500,000 tokens. Only GPT-5.5 Pro specifies output context (128,000 tokens).

OpenAI
GPT-5.5 Pro
Input1,050,000 tokens
Output128,000 tokens
xAI
Grok 4.5
Input500,000 tokens
Output- tokens
Fri Jul 17 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both GPT-5.5 Pro and Grok 4.5 support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

GPT-5.5 Pro

Text
Images
Audio
Video

Grok 4.5

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

GPT-5.5 Pro

Proprietary

Closed source

Grok 4.5

Proprietary

Closed source

Release Timeline

When each model was launched

GPT-5.5 Pro 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 Pro.

GPT-5.5 Pro

Apr 23, 2026

2 months ago

Grok 4.5

Jul 8, 2026

1 weeks ago

2mo newer

Knowledge Cutoff

When training data ends

GPT-5.5 Pro 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 Pro's training data extends to 2025-12-01, but cannot make a direct comparison without Grok 4.5's cutoff date.

GPT-5.5 Pro

Dec 2025

Grok 4.5

—

Provider Availability

GPT-5.5 Pro is available from OpenAI. Grok 4.5 is available from xAI.

GPT-5.5 Pro

openai logo
OpenAI
Input Price:Input: $30.00/1MOutput Price:Output: $180.00/1M

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
Larger context window (1,050,000 tokens)
xAI
Less expensive input tokens
Less expensive output tokens

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against GPT-5.5 Pro and Grok 4.5 side-by-side, then vote on the output you prefer.

GPT-5.5 Pro
✓ Preferred
Grok 4.5
Open in Playground
AI Model Comparison Table
Feature
OpenAI
GPT-5.5 Pro
xAI
Grok 4.5

FAQ

Common questions about GPT-5.5 Pro vs Grok 4.5.

Which is better, GPT-5.5 Pro or Grok 4.5?

GPT-5.5 Pro (OpenAI) and Grok 4.5 (xAI) each have strengths in different areas. Compare their benchmark scores, pricing, context windows, and capabilities above to determine which fits your needs.

How does GPT-5.5 Pro compare to Grok 4.5 in benchmarks?

GPT-5.5 Pro scores BrowseComp: 90.1%, GDPval-MM: 82.3%, Humanity's Last Exam: 57.2%, FrontierMath: 39.6%, GeneBench: 33.2%. 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-5.5 Pro cheaper than Grok 4.5?

Grok 4.5 is 15.0x cheaper for input tokens. GPT-5.5 Pro costs $30.00/M input and $180.00/M output via openai. Grok 4.5 costs $2.00/M input and $6.00/M output via xai.

What are the context window sizes for GPT-5.5 Pro and Grok 4.5?

GPT-5.5 Pro supports 1.1M 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-5.5 Pro and Grok 4.5?

Key differences include context window (1.1M vs 500K), input pricing ($30.00 vs $2.00/M). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-5.5 Pro and Grok 4.5?

GPT-5.5 Pro is developed by OpenAI and Grok 4.5 is developed by xAI.

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