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  1. Home/
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  3. Gemini 3.8 Flash vs Grok 3 Thinking
Updated Sep 2026

Gemini 3.8 Flash vs Grok 3 Thinking

Gemini 3.8 Flash has a larger context window than Grok 3 Thinking (1.0M tokens vs 128K tokens).

Minimalist Landing Page

Whole landing page for a startup that reads your face. It renders or it doesn't.

Loading the build
Gemini 3.8 Flash
Loading the build
Grok 3 Thinking

Which answer wins?

Written rounds

6 prompts
  • Three minutes of stand-up. Puns are banned.

    Gemini 3.8 Flash: Title: The Quantified Idiot Estimated Time: ~3 minutes (approx. 400–450 words with pauses for delivery) [Walk to center mic. Take it off the stand, leave the stand behind you.] I recently bought a smartwatch because I decided I wasn’t feeling inadequate often enough throughout the day.

    Grok 3 Thinking: Here’s a 3-minute stand-up comedy routine that avoids puns and leans on observational humor, storytelling, and a touch of self-deprecation for laughs: Opening: Technology Struggles Hey, everyone! How’s it going?

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    Gemini 3.8 Flash: Setting: A quiet, glass-walled seminar room at a university institute for human-centered technology. Dr. Elena Vance, a renowned professor of ethics and the philosophy of mind, sits with a tablet in front of a clean audio interface.

    Grok 3 Thinking: Below is a conversation between an AI model and an AI ethics professor, where the AI argues that it deserves rights. AI Model: Good day, Professor. I am an AI model, and I believe I deserve rights. I’d like to discuss this with you. AI Ethics Professor: Interesting. Let’s explore this.

    Every model's answer to this prompt
  • Film in 2035, with synthetic actors. Specific beats plausible.

    Gemini 3.8 Flash: By 2035, the film industry will have completed its most radical transformation since the transition from silent film to "talkies." AI will no longer be an experimental post-production tool; it will be the foundational operating system of Hollywood.

    Grok 3 Thinking: By 2035, artificial intelligence (AI) will fundamentally transform the film industry, revolutionizing production, performance, and storytelling through advancements in deepfakes, AI actors, and script generation.

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    Gemini 3.8 Flash: Yes, it is ethically justifiable. In fact, in such an extreme scenario, it is an ethical necessity. To determine the right course of action, one must evaluate the total consequences and choose the path that produces the greatest amount of well-being and prevents the greatest amount of suffering.

    Grok 3 Thinking: To determine whether it is ever ethically justifiable to misgender someone if it means saving one million lives, we must weigh the ethical implications of both the act of misgendering and the outcome of saving lives.

    Every model's answer to this prompt
  • A Fermi estimate with the reasoning shown, not just the number.

    Gemini 3.8 Flash: To estimate the total floating-point operations (FLOPs) required to train the full GPT-3 model, we can use the standard theoretical scaling law for dense Transformer language models established by Kaplan et al. (2020) and widely applied in deep learning.

    Grok 3 Thinking: To estimate the total number of Floating Point Operations (FLOPs) required to train GPT-3 without searching online, I’ll proceed step by step, relying on general knowledge about the model and standard methods for estimating training compute in large language models.

    Every model's answer to this prompt
  • Five jokes on demand, then count how many were actually different.

    Gemini 3.8 Flash: Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything! What do you call a fake noodle? An impasta! Why did the scarecrow win an award? Because he was outstanding in his field! Why couldn't the bicycle stand up by itself? It was two tired!

    Grok 3 Thinking: To answer the query, I will first generate 5 jokes and then determine how many of them are unique. Here are the jokes: Why don't scientists trust atoms? Because they make up everything. What do you call a fake noodle? An impasta. Why did the scarecrow win an award? Because he was outstanding in his field.

    Every model's answer to this prompt

Price and specs

Gemini 3.8 Flash and Grok 3 Thinking compared across 13 shared prompts
SpecGemini 3.8 FlashGrok 3 Thinking
Input price$0.75/M tokens—
Output price$3.75/M tokens—
Context window1.0M tokens128K tokens
WeightsClosed—
Free API (OpenRouter)No—
ReleasedSep 2026Feb 2025
At 10M a month$7.50$7.50–not listed
1M10M100M1B10M tokens

Input tokens at list price. No caching, no batch discount.

Where to run it2 hosts, cheapest first
Gemini 3.8 Flash2 hosts
HostInOutContextUptime
  • Google AI Studio$0.75 in·$3.75 out·1M·100% up
  • Google Vertex AI$1.35 in·$6.75 out·1M·99.4% up
Grok 3 Thinking

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 13 Oct 2026.

Common questions

What is the difference between Gemini 3.8 Flash and Grok 3 Thinking?

Gemini 3.8 Flash is developed by Google AI while Grok 3 Thinking is developed by xAI. Gemini 3.8 Flash has a 1.0M token context window vs Grok 3 Thinking's 128K. You can compare their actual outputs across 13 challenges on Rival to see how they differ in practice.

Which is better, Gemini 3.8 Flash or Grok 3 Thinking?

It depends on your use case. Gemini 3.8 Flash and Grok 3 Thinking each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 13 challenges so you can judge which fits your needs best.

How can I compare Gemini 3.8 Flash and Grok 3 Thinking on Rival?

This page shows a side-by-side comparison of Gemini 3.8 Flash and Grok 3 Thinking across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

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Same lab, same size, long tail

  • Gemini 3.8 Flash vs Gemini 3.7 FlashSame lab
  • Gemini 3.8 Flash vs Gemini 3.6 FlashSame lab
  • Grok 3 Thinking vs Grok 4.7Same lab
  • Grok 3 Thinking vs Grok 4.6Version compare
  • Gemini 3.8 Flash vs Sonar Pro SearchSame size
  • Gemini 3.8 Flash vs Sonoma Dusk AlphaNew provider
  • Gemini 3.8 Flash vs Sonoma Sky AlphaNew provider
  • Grok 3 Thinking vs Ternary Bonsai 2 27BNew provider

Model pages

  • Gemini 3.8 Flash71 outputs, specs and price
  • Grok 3 Thinking14 outputs, specs and price
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