Model Comparison

GPT-5.6 Luna vs Grok-2Which is better in 2026?

GPT-5.6 Luna significantly outperforms across most benchmarks. GPT-5.6 Luna is 1.8x cheaper per token.

Verdict: GPT-5.6 Luna vs Grok-2 — which is better?

GPT-5.6 Luna (by OpenAI) and Grok-2 (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 Luna outperforms in 1 benchmarks (GPQA), while Grok-2 is better at 0 benchmarks. GPT-5.6 Luna significantly outperforms across most benchmarks.

On price, GPT-5.6 Luna is roughly 1.8x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

GPT-5.6 Luna 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 Luna if…

  • you want the strongest raw capability — it leads on 1 of 1 shared benchmarks
  • cost matters — it's about 1.8x cheaper per token
  • 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-2 if…

  • you want predictable pricing at $2.00/M input and $10.00/M output

Performance Benchmarks

Comparative analysis across standard metrics

1 benchmarks

GPT-5.6 Luna outperforms in 1 benchmarks (GPQA), while Grok-2 is better at 0 benchmarks.

GPT-5.6 Luna significantly outperforms across most benchmarks.

Sat Jul 18 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

GPT-5.6 Luna costs less

For input processing, GPT-5.6 Luna ($1.00/1M tokens) is 2.0x cheaper than Grok-2 ($2.00/1M tokens).

For output processing, GPT-5.6 Luna ($6.00/1M tokens) is 1.7x cheaper than Grok-2 ($10.00/1M tokens).

In conclusion, Grok-2 is more expensive than GPT-5.6 Luna.*

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

Lowest available price from all providers
Sat Jul 18 2026 • llm-stats.com
OpenAI
GPT-5.6 Luna
Input tokens$1.00
Output tokens$6.00
Best providerOpenAI
xAI
Grok-2
Input tokens$2.00
Output tokens$10.00
Best providerxAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

GPT-5.6 Luna accepts 1,050,000 input tokens compared to Grok-2's 128,000 tokens. GPT-5.6 Luna can generate longer responses up to 128,000 tokens, while Grok-2 is limited to 8,000 tokens.

OpenAI
GPT-5.6 Luna
Input1,050,000 tokens
Output128,000 tokens
xAI
Grok-2
Input128,000 tokens
Output8,000 tokens
Sat Jul 18 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both GPT-5.6 Luna and Grok-2 support multimodal inputs.

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

GPT-5.6 Luna

Text
Images
Audio
Video

Grok-2

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-5.6 Luna

Proprietary

Closed source

Grok-2

Proprietary

Closed source

Release Timeline

When each model was launched

GPT-5.6 Luna was released on 2026-07-09, while Grok-2 was released on 2024-08-13.

GPT-5.6 Luna is 23 months newer than Grok-2.

GPT-5.6 Luna

Jul 9, 2026

1 weeks ago

1.9yr newer
Grok-2

Aug 13, 2024

1.9 years ago

Knowledge Cutoff

When training data ends

GPT-5.6 Luna has a documented knowledge cutoff of 2026-02-16, while Grok-2's cutoff date is not specified.

We can confirm GPT-5.6 Luna's training data extends to 2026-02-16, but cannot make a direct comparison without Grok-2's cutoff date.

GPT-5.6 Luna

Feb 2026

Grok-2

—

Provider Availability

GPT-5.6 Luna is available from OpenAI. Grok-2 is available from xAI.

GPT-5.6 Luna

openai logo
OpenAI
Input Price:Input: $1.00/1MOutput Price:Output: $6.00/1M

Grok-2

xai logo
xAI
Input Price:Input: $2.00/1MOutput Price:Output: $10.00/1M
* 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)
Less expensive input tokens
Less expensive output tokens
Higher GPQA score (92.3% vs 56.0%)
xAI

No standout differentiators in the data we have for this pair.

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against GPT-5.6 Luna and Grok-2 side-by-side, then vote on the output you prefer.

GPT-5.6 Luna
✓ Preferred
Grok-2
Open in Playground
AI Model Comparison Table
Feature
OpenAI
GPT-5.6 Luna
xAI
Grok-2

FAQ

Common questions about GPT-5.6 Luna vs Grok-2.

Which is better, GPT-5.6 Luna or Grok-2?

GPT-5.6 Luna significantly outperforms across most benchmarks. GPT-5.6 Luna is made by OpenAI and Grok-2 is made by xAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does GPT-5.6 Luna compare to Grok-2 in benchmarks?

GPT-5.6 Luna scores Connectors: 99.9%, HealthBench Consensus: 95.1%, GPQA: 92.3%, Search and Function-Calling: 89.7%, Capture-the-Flag Challenges (Internal): 85.2%. Grok-2 scores DocVQA: 93.6%, HumanEval: 88.4%, MMLU: 87.5%, MATH: 76.1%, MMLU-Pro: 75.5%.

Is GPT-5.6 Luna cheaper than Grok-2?

GPT-5.6 Luna is 2.0x cheaper for input tokens. GPT-5.6 Luna costs $1.00/M input and $6.00/M output via openai. Grok-2 costs $2.00/M input and $10.00/M output via xai.

What are the context window sizes for GPT-5.6 Luna and Grok-2?

GPT-5.6 Luna supports 1.1M tokens and Grok-2 supports 128K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-5.6 Luna and Grok-2?

Key differences include context window (1.1M vs 128K), input pricing ($1.00 vs $2.00/M). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-5.6 Luna and Grok-2?

GPT-5.6 Luna is developed by OpenAI and Grok-2 is developed by xAI.

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