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Gemini 3.8 Flash vs Grok-4 Heavy

Gemini 3.8 Flash leads the LLM Stats Score 51.0 to 40.9.

Google · xAI · Updated for 2026

Which is better?

Gemini 3.8 Flash leads the overall LLM Stats Score 51.0 to 40.9, ranking #15 overall.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose Gemini 3.8 Flash

  • overall performance matters — it scores 51.0 and ranks #15 on LLM Stats
  • your work emphasizes coding — it leads those capability indexes

Choose Grok-4 Heavy

  • you are already invested in the xAI ecosystem

At a glance

The differences that matter most.

Gemini 3.8 Flash
Google
Grok-4 Heavy
xAI
Core performance indexes
LLM Stats Score
51.0
#15
40.9
#50
Reasoning
46.9
#24
39.2
#53
Coding
39.3
#14
17.9
#108
Cost, coverage & limits
Benchmark wins
—
—
Input price
$0.75 / M
— / M
Output price
$3.75 / M
— / M
Context window
1,048,576
—

Individual benchmarks

13 reported for Gemini 3.8 Flash · 6 for Grok-4 Heavy

No common benchmarks found

Gemini 3.8 Flash and Grok-4 Heavydon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Human preference

Blind head-to-head votes and playground preference scores

Context Window

Maximum input and output token capacity

Only Gemini 3.8 Flash specifies input context (1,048,576 tokens). Only Gemini 3.8 Flash specifies output context (65,536 tokens).

Google
Gemini 3.8 Flash
Input1,048,576 tokens
Output65,536 tokens
xAI
Grok-4 Heavy
Input- tokens
Output- tokens
Fri Sep 04 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both Gemini 3.8 Flash and Grok-4 Heavy support multimodal inputs.

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

Gemini 3.8 Flash

Text
Images
Audio
Video

Grok-4 Heavy

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 3.8 Flash

Proprietary

Closed source

Grok-4 Heavy

Proprietary

Closed source

Release Timeline

When each model was launched

Gemini 3.8 Flash was released on 2026-09-02, while Grok-4 Heavy's release date is not specified.

We can confirm Gemini 3.8 Flash's release timeline, but cannot make a direct age comparison without Grok-4 Heavy's release date.

Gemini 3.8 Flash

Sep 2, 2026

2 days ago

Grok-4 Heavy

—

Knowledge Cutoff

When training data ends

Gemini 3.8 Flash has a knowledge cutoff of 2026-03-31, while Grok-4 Heavy has a cutoff of 2024-12-31.

Gemini 3.8 Flash has more recent training data (up to 2026-03-31), making it potentially better informed about events through that date compared to Grok-4 Heavy (2024-12-31).

Gemini 3.8 Flash

Mar 2026

1.3 yr newer
Grok-4 Heavy

Dec 2024

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Judge for yourself.

Run your own prompts against Gemini 3.8 Flash and Grok-4 Heavy side-by-side, then vote on the output you prefer.

Gemini 3.8 Flash
✓ Preferred
Grok-4 Heavy
Open in Playground

FAQ

Common questions about Gemini 3.8 Flash vs Grok-4 Heavy.

Which is better, Gemini 3.8 Flash or Grok-4 Heavy?

Gemini 3.8 Flash leads the LLM Stats Score 51.0 to 40.9. Gemini 3.8 Flash is made by Google and Grok-4 Heavy is made by xAI. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does Gemini 3.8 Flash compare to Grok-4 Heavy in benchmarks?

Gemini 3.8 Flash scores Terminal-Bench 2.1: 89.4%, LVBench: 87.1%, CharXiv-R: 86.2%, LABBench2: 86.2%, DeepSWE 1.1: 73.7%. Grok-4 Heavy scores AIME 2025: 100.0%, HMMT25: 96.7%, GPQA: 88.4%, LiveCodeBench: 79.4%, USAMO25: 61.9%.

What are the context window sizes for Gemini 3.8 Flash and Grok-4 Heavy?

Gemini 3.8 Flash supports 1.0M tokens and Grok-4 Heavy 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 3.8 Flash and Grok-4 Heavy?

Key differences include LLM Stats Score (51.0 vs 40.9). See the full comparison above for benchmark-by-benchmark results.

Who makes Gemini 3.8 Flash and Grok-4 Heavy?

Gemini 3.8 Flash is developed by Google and Grok-4 Heavy is developed by xAI.

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