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Gemini 3.8 Flash vs Grok-1.5

Gemini 3.8 Flash leads the LLM Stats Score 51.8 to -2.4.

Google · xAI · Updated for 2026

Which is better?

Gemini 3.8 Flash leads the overall LLM Stats Score 51.8 to -2.4, ranking #11 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 51.8 and ranks #11 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you want the most recent training data — it shipped Sep 2026

Choose Grok-1.5

  • you are already invested in the xAI ecosystem

At a glance

The differences that matter most.

Gemini 3.8 Flash
Google
Grok-1.5
xAI
Core performance indexes
LLM Stats Score
51.8
#11
-2.4
#326
Reasoning
47.6
#21
-1.9
#316
Coding
41.3
#10
-0.8
#235
Cost, coverage & limits
Benchmark wins
—
—
Input price
$0.75 / M
— / M
Output price
$3.75 / M
— / M
Context window
1,048,576
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

2 shared
Index
Gemini 3.8 Flash
Grok-1.5
Vision
34.4#11
-4.8#195
Multimodal
35.3#10
-2.2#154
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

13 reported for Gemini 3.8 Flash · 9 for Grok-1.5

No common benchmarks found

Gemini 3.8 Flash and Grok-1.5don'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-1.5
Input- tokens
Output- tokens
Wed Sep 02 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Gemini 3.8 Flash supports multimodal inputs, whereas Grok-1.5 does not.

Gemini 3.8 Flash can handle both text and other forms of data like images, making it suitable for multimodal applications.

Gemini 3.8 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 3.8 Flash

Proprietary

Closed source

Grok-1.5

Proprietary

Closed source

Release Timeline

When each model was launched

Gemini 3.8 Flash was released on 2026-09-02, while Grok-1.5 was released on 2024-03-28.

Gemini 3.8 Flash is 30 months newer than Grok-1.5.

Gemini 3.8 Flash

Sep 2, 2026

0 days ago

2.4yr newer
Grok-1.5

Mar 28, 2024

2.4 years ago

Knowledge Cutoff

When training data ends

Gemini 3.8 Flash has a documented knowledge cutoff of 2026-03-31, while Grok-1.5's cutoff date is not specified.

We can confirm Gemini 3.8 Flash's training data extends to 2026-03-31, but cannot make a direct comparison without Grok-1.5's cutoff date.

Gemini 3.8 Flash

Mar 2026

Grok-1.5

—

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-1.5 side-by-side, then vote on the output you prefer.

Gemini 3.8 Flash
✓ Preferred
Grok-1.5
Open in Playground

FAQ

Common questions about Gemini 3.8 Flash vs Grok-1.5.

Which is better, Gemini 3.8 Flash or Grok-1.5?

Gemini 3.8 Flash leads the LLM Stats Score 51.8 to -2.4. Gemini 3.8 Flash is made by Google and Grok-1.5 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-1.5 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-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 3.8 Flash and Grok-1.5?

Gemini 3.8 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 3.8 Flash and Grok-1.5?

Key differences include LLM Stats Score (51.8 vs -2.4), multimodal support (yes vs no). See the full comparison above for benchmark-by-benchmark results.

Who makes Gemini 3.8 Flash and Grok-1.5?

Gemini 3.8 Flash is developed by Google and Grok-1.5 is developed by xAI.

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