Gemini 3.8 Flash vs Grok 4 Fast
Gemini 3.8 Flash leads the LLM Stats Score 51.0 to 32.0. Grok 4 Fast is 5.5x cheaper per token.
Google · xAI · Updated for 2026
Which is better?
Gemini 3.8 Flash leads the overall LLM Stats Score 51.0 to 32.0, ranking #15 overall.
On price, Grok 4 Fast is roughly 5.5x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Grok 4 Fast also accepts a larger context window (2,000,000 input tokens), making it the stronger choice for long documents and large codebases.
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 reasoning and coding — it leads those capability indexes
- you want the most recent training data — it shipped Sep 2026
Choose Grok 4 Fast
- cost matters — it's about 5.5x cheaper per token
- you process long inputs — it offers a 2,000,000 token context window
At a glance
The differences that matter most.
Individual benchmarks
13 reported for Gemini 3.8 Flash · 7 for Grok 4 Fast
Gemini 3.8 Flash and Grok 4 Fastdon'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
Pricing Analysis
Price comparison per million tokens
For input processing, Gemini 3.8 Flash ($0.75/1M tokens) is 3.8x more expensive than Grok 4 Fast ($0.20/1M tokens).
For output processing, Gemini 3.8 Flash ($3.75/1M tokens) is 7.5x more expensive than Grok 4 Fast ($0.50/1M tokens).
In conclusion, Gemini 3.8 Flash is more expensive than Grok 4 Fast.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Grok 4 Fast accepts 2,000,000 input tokens compared to Gemini 3.8 Flash's 1,048,576 tokens. Gemini 3.8 Flash can generate longer responses up to 65,536 tokens, while Grok 4 Fast is limited to 30,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Gemini 3.8 Flash and Grok 4 Fast support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Gemini 3.8 Flash
Grok 4 Fast
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Gemini 3.8 Flash was released on 2026-09-02, while Grok 4 Fast was released on 2025-08-28.
Gemini 3.8 Flash is 12 months newer than Grok 4 Fast.
Sep 2, 2026
2 days ago
1.0yr newerAug 28, 2025
1.0 years ago
Knowledge Cutoff
When training data ends
Gemini 3.8 Flash has a documented knowledge cutoff of 2026-03-31, while Grok 4 Fast'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 4 Fast's cutoff date.
Mar 2026
—
Provider Availability
Gemini 3.8 Flash is available from Google. Grok 4 Fast is available from xAI.
Gemini 3.8 Flash
Grok 4 Fast
Outputs Comparison
Judge for yourself.
Run your own prompts against Gemini 3.8 Flash and Grok 4 Fast side-by-side, then vote on the output you prefer.
FAQ
Common questions about Gemini 3.8 Flash vs Grok 4 Fast.