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Model Comparison

Gemini 1.5 Flash vs Grok-1.5Which is better in 2026?

Gemini 1.5 Flash shows notably better performance in the majority of benchmarks.

Verdict: Gemini 1.5 Flash vs Grok-1.5 — which is better?

Gemini 1.5 Flash (by Google) and Grok-1.5 (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.

Gemini 1.5 Flash outperforms in 6 benchmarks (GPQA, HumanEval, MATH, MathVista, MMLU-Pro, MMMU), while Grok-1.5 is better at 2 benchmarks (GSM8k, MMLU). Gemini 1.5 Flash shows notably better performance in the majority of benchmarks.

Choose Gemini 1.5 Flash if…

  • you want the strongest raw capability — it leads on 6 of 8 shared benchmarks
  • you want the most recent training data — it shipped May 2024

Choose Grok-1.5 if…

  • you are already invested in the xAI ecosystem

Performance Benchmarks

Comparative analysis across standard metrics

8 benchmarks

Gemini 1.5 Flash outperforms in 6 benchmarks (GPQA, HumanEval, MATH, MathVista, MMLU-Pro, MMMU), while Grok-1.5 is better at 2 benchmarks (GSM8k, MMLU).

Gemini 1.5 Flash shows notably better performance in the majority of benchmarks.

Thu Aug 06 2026 • llm-stats.com

Arena Performance

Human preference votes

Context Window

Maximum input and output token capacity

Only Gemini 1.5 Flash specifies input context (1,048,576 tokens). Only Gemini 1.5 Flash specifies output context (8,192 tokens).

Google
Gemini 1.5 Flash
Input1,048,576 tokens
Output8,192 tokens
xAI
Grok-1.5
Input- tokens
Output- tokens
Thu Aug 06 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Gemini 1.5 Flash supports multimodal inputs, whereas Grok-1.5 does not.

Gemini 1.5 Flash can handle both text and other forms of data like images, making it suitable for multimodal applications.

Gemini 1.5 Flash

Text
Images
Audio
Video

Grok-1.5

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.

Gemini 1.5 Flash

Proprietary

Closed source

Grok-1.5

Proprietary

Closed source

Release Timeline

When each model was launched

Gemini 1.5 Flash was released on 2024-05-01, while Grok-1.5 was released on 2024-03-28.

Gemini 1.5 Flash is 1 month newer than Grok-1.5.

Gemini 1.5 Flash

May 1, 2024

2.3 years ago

1mo newer
Grok-1.5

Mar 28, 2024

2.4 years ago

Knowledge Cutoff

When training data ends

Gemini 1.5 Flash has a documented knowledge cutoff of 2023-11-01, while Grok-1.5's cutoff date is not specified.

We can confirm Gemini 1.5 Flash's training data extends to 2023-11-01, but cannot make a direct comparison without Grok-1.5's cutoff date.

Gemini 1.5 Flash

Nov 2023

Grok-1.5

—

Outputs Comparison

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Key Takeaways

Google
Larger context window (1,048,576 tokens)
Supports multimodal inputs
Higher GPQA score (51.0% vs 35.9%)
Higher HumanEval score (74.3% vs 74.1%)
Higher MATH score (77.9% vs 50.6%)
Higher MathVista score (65.8% vs 52.8%)
Higher MMLU-Pro score (67.3% vs 51.0%)
Higher MMMU score (62.3% vs 53.6%)
xAI
Higher GSM8k score (90.0% vs 86.2%)
Higher MMLU score (81.3% vs 78.9%)
GoogleGemini 1.5 Flash
xAIGrok-1.5
Compare in Playground

Detailed Comparison

Interactive Arena

Judge for yourself.

Run your own prompts against Gemini 1.5 Flash and Grok-1.5 side-by-side, then vote on the output you prefer.

Gemini 1.5 Flash
✓ Preferred
Grok-1.5
Open in Playground
AI Model Comparison Table
Feature
Google
Gemini 1.5 Flash
xAI
Grok-1.5

FAQ

Common questions about Gemini 1.5 Flash vs Grok-1.5.

Which is better, Gemini 1.5 Flash or Grok-1.5?

Gemini 1.5 Flash shows notably better performance in the majority of benchmarks. Gemini 1.5 Flash is made by Google and Grok-1.5 is made by xAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.

How does Gemini 1.5 Flash compare to Grok-1.5 in benchmarks?

Gemini 1.5 Flash scores XSTest: 97.0%, FLEURS: 90.4%, HellaSwag: 86.5%, GSM8k: 86.2%, BIG-Bench Hard: 85.5%. Grok-1.5 scores GSM8k: 90.0%, DocVQA: 85.6%, MMLU: 81.3%, HumanEval: 74.1%, MMMU: 53.6%.

What are the context window sizes for Gemini 1.5 Flash and Grok-1.5?

Gemini 1.5 Flash supports 1.0M tokens and Grok-1.5 supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between Gemini 1.5 Flash and Grok-1.5?

Key differences include multimodal support (yes vs no). See the full comparison above for benchmark-by-benchmark results.

Who makes Gemini 1.5 Flash and Grok-1.5?

Gemini 1.5 Flash is developed by Google and Grok-1.5 is developed by xAI.

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