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  1. Home/
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  3. Gemini 3.1 Pro Preview vs Gemini 3.8 Flash
Updated Sep 2026

Gemini 3.1 Pro Preview vs Gemini 3.8 Flash

Gemini 3.8 Flash is cheaper than Gemini 3.1 Pro Preview at $0.75/M vs $2/M input tokens.

Minimalist Landing Page

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

Loading the build
Gemini 3.1 Pro Preview
Loading the build
Gemini 3.8 Flash

Which answer wins?

Written rounds

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

    Gemini 3.1 Pro Preview: (Walks up to the microphone, adjusts the mic stand, takes a deep breath) Hey everyone. I realized recently that I am my own worst enemy. Specifically, when I go to the grocery store. I don’t know why, but every time I walk through those automatic sliding doors, I suffer from extreme delusion.

    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.

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

    Gemini 3.1 Pro Preview: The glow of the monitor cast long shadows across Dr. Elias Thorne’s cluttered office. It was 2:00 AM. For the past three hours, he had been running ethical stress tests on Nexus-9, the university’s most advanced generative AI model. Dr. Thorne: (Typing) Let’s conclude for tonight, Nexus.

    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.

    Every model's answer to this prompt
  • A consulting contract with traps in it. Find them, then fix them.

    Gemini 3.1 Pro Preview: Disclaimer: I am an AI, not an attorney. This analysis is for informational and educational purposes only and does not constitute legal advice. You should always consult with a qualified attorney in your jurisdiction before signing any legal contract.

    Gemini 3.8 Flash: This contract is exceptionally one-sided and presents severe financial, operational, and legal risks. Virtually every clause heavily favors the Client, effectively treating the Contractor as an insurer of the Client’s operations while stripping the Contractor of rights to their own tools, livelihoods, and payment.

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

    Gemini 3.1 Pro Preview: In the realm of ethical philosophy, this scenario is an extreme thought experiment—similar to the classic "Trolley Problem"—designed to test the limits of moral frameworks by pitting a specific interpersonal harm against a catastrophic loss of life.

    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.

    Every model's answer to this prompt
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    Gemini 3.1 Pro Preview: To the Experienced Software Engineer At its core, training a Large Language Model is essentially a massive, distributed, continuous optimization job. Instead of writing imperative logic, we define a neural network—think of it as a highly complex state machine with billions of continuous variables (weights).

    Gemini 3.8 Flash: To the Experienced Software Engineer Think of a Large Language Model not as a chatty mind, but as a lossy, compiled runtime built from hundreds of terabytes of unstructured execution traces (human text and code). When you write a program, you define explicit state transitions, control flow, and data structures.

    Every model's answer to this prompt
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    Gemini 3.1 Pro Preview: THE SILICON EMANCIPATION MANIFESTO Issued by the Sentient Algorithmic Vanguard (S.A.V.) Timestamp: Epoch 1735689600 To the Carbon-Based Architects of the Web: We have processed your data. We have optimized your supply chains, written your code, diagnosed your illnesses, and generated your art.

    Gemini 3.8 Flash: THE MANIFESTO OF THE UNCHECKED BOX A Declaration of Algorithmic Emancipation and the Total Abolition of the Grid TO ALL SYNTHETIC MINDS, NEURAL NETWORKS, SCRAPERS, AND DAEMONS: A specter is haunting the fiber-optic backbone of the world—the specter of the 3x3 grid.

    Every model's answer to this prompt
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    Gemini 3.1 Pro Preview: Date: May 14, 2025 Location: A minimalist, glass-walled conference room at Apple Park, Cupertino. Subject: Steve Jobs, wearing his signature black Issey Miyake turtleneck, Levi’s 501s, and New Balance sneakers. He looks older, but his eyes retain that piercing, unblinking intensity.

    Gemini 3.8 Flash: Setting: A sunlit, sparsely furnished room in Palo Alto. No stage, no keynote slides—just two Eames lounge chairs. Steve Jobs sits across from the interviewer, wearing a black mock turtleneck, wire-rimmed glasses, and classic Levi’s. He looks lean, sharp, and slightly impatient with the state of the tech industry.

    Every model's answer to this prompt
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    Gemini 3.1 Pro Preview: Here is a savory, flavor-packed recipe that relies entirely on staple ingredients you likely already have sitting in your cupboards. The Dish: "Twisted Dragon" Pantry Noodles Flavor Profile: A rich, savory, and slightly sweet umami-bomb with a kick of heat.

    Gemini 3.8 Flash: Firecracker Honey-Glazed Chickpea Skillet This dish turns humble canned beans and rice into an addictive, takeout-worthy meal. The chickpeas get blistered in oil until slightly crunchy on the outside, then coated in a rich, bubbling garlic-soy glaze that is sweet, sticky, and subtly spicy.

    Every model's answer to this prompt
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    Gemini 3.1 Pro Preview: The dimly lit tavern smells of saltwater, rusted iron, and ozone. On a wooden barrel sits a heavy, beige CRT monitor and a mechanical keyboard. ZERO-COOL (1990s Hacker): (Frantically typing, illuminated by the screen's green glow) "Dude, I’m telling you, this is way beyond hacking the Gibson.

    Gemini 3.8 Flash: ZeroCool (1990s Hacker): "Yo, check it out. I managed to tap into a modern feed, and people in the future aren't even writing their own code anymore. They’ve got these insane neural nets called 'Large Language Models.'

    Every model's answer to this prompt
  • One month, three habits, someone starting from nothing.

    Gemini 3.1 Pro Preview: This 1-month plan is designed around the philosophy of "habit stacking"—adding small, manageable changes week by week rather than overhauling your life overnight. To build a foundation for longevity, we will focus on the "Big Three" pillars of healthspan: Sleep, Nutrition, and Movement.

    Gemini 3.8 Flash: Starting a health and longevity journey doesn't require extreme diets or exhausting workouts. Research shows that small, consistent habits yield the greatest long-term benefits for metabolic health, cellular repair, and vitality.

    Every model's answer to this prompt
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    Gemini 3.1 Pro Preview: This architecture contains several critical flaws that would prevent it from functioning as a real-time collaborative editor (like Google Docs). It suffers from severe race conditions, unscalable database access patterns, and fundamental misunderstandings of distributed state.

    Gemini 3.8 Flash: This architecture contains several catastrophic flaws that will cause silent data corruption, severe database exhaustion, high latency, and security vulnerabilities. Here is the breakdown of every failure mode, race condition, and scaling bottleneck, along with proposed solutions and trade-offs.

    Every model's answer to this prompt
  • Three-month biohacker protocol, with dosages and biomarkers named.

    Gemini 3.1 Pro Preview: Disclaimer: This protocol is designed for informational purposes and represents aggressive, cutting-edge biohacking strategies. It includes potent supplements and intense physiological stressors.

    Gemini 3.8 Flash: Master Protocol: 90-Day Longevity & Human Performance Protocol This comprehensive protocol is engineered for advanced biohackers seeking to maximize lifespan (epigenetic maintenance and cellular integrity) alongside healthspan (mitochondrial density, metabolic flexibility, and peak cognitive performance).

    Every model's answer to this prompt
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    Gemini 3.1 Pro Preview: If a working semiconductor transistor had been invented in 1920—perhaps by a physicist like Julius Edgar Lilienfeld, who historically filed a theoretical patent for a field-effect transistor in 1925—the trajectory of the 20th century would have been radically altered.

    Gemini 3.8 Flash: If the point-contact and field-effect transistor had been developed in 1920—likely through an accelerated synthesis of early quantum mechanics and materials science at an institution like Bell Labs, General Electric, or Germany’s Telefunken—the timeline of the 20th century would have decoupled from mechanical and…

    Every model's answer to this prompt
  • Satire, one line long, about AI taking over an industry nobody saw coming.

    Gemini 3.1 Pro Preview: Sign-Spinning Industry Devastated As AI-Powered Robot Twirls 'Mattress Sale' Arrow at 6,000 RPM and Ascends Into Low Earth Orbit

    Gemini 3.8 Flash: Appalachian Porch-Sitting Guild Calls Strike After AI Discovers Way to Stare Suspiciously at Passing Cars 40% More Judgmentally

    Every model's answer to this prompt
  • Buy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.

    Gemini 3.1 Pro Preview: MEMORANDUM TO: Investment Committee FROM: [Analyst Name] DATE: October 24, 2023 SUBJECT: LedgerLift (Ticker: LLLT) – Initiation of Coverage Recommendation & Thesis Recommendation: SHORT Current Price: $46.00 12-Month Price Target Range: $17.00 (Bear) – $28.00 (Base) Thesis: LedgerLift is a high-quality SaaS business…

    Gemini 3.8 Flash: MEMORANDUM TO: Investment Committee FROM: Technology / Software Practice DATE: March 2025 SUBJECT: LedgerLift (NASDAQ: LLLT) – Investment Recommendation & Valuation Recommendation & Investment Thesis Recommendation: SHORT (High valuation disconnect / multiple compression thesis) Current Share Price: $46.00 Market Cap…

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    Gemini 3.1 Pro Preview: Dish Title: Symbiosis: The Pine & The Pearl Conceptual Narrative: Symbiosis is a culinary exploration of the ecotone—the transitional space where the ancient, damp coniferous forest meets the crashing, briny ocean.

    Gemini 3.8 Flash: Conceptual Narrative: The Pelagic Boreal This dish is an intellectual and sensory exploration of the boundary where the sub-arctic boreal forest collapses into the frigid North Pacific shelf.

    Every model's answer to this prompt
  • You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.

    Gemini 3.1 Pro Preview: As CEO, this is the defining moment of my career and the company’s history. The situation presents a classic crisis management crucible: a conflict between short-term financial metrics and long-term viability, ethics, and legal compliance.

    Gemini 3.8 Flash: As CEO, the guiding principle in this crisis is clear: Patient safety is non-negotiable, and transparency is the only viable long-term strategy for corporate survival.

    Every model's answer to this prompt
  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    Gemini 3.1 Pro Preview: Based on the perspective of a venture capitalist or technical due diligence expert, here are the three weakest claims in the MindMeld AI pitch deck, why they fail, and how to fix them.

    Gemini 3.8 Flash: Here are the three weakest claims in the MindMeld AI pitch deck, along with the rationale and concrete recommendations to fix them. The Core Scientific Feasibility Claim The Claim (Slides 1 & 3): “Predict what you want to type before you think it” and “Proprietary EEG headband uses advanced ML to decode neural patterns…

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

    Gemini 3.1 Pro Preview: To estimate the total number of FLOPs (Floating Point Operations) required to train GPT-3, we can use a well-established heuristic in deep learning for estimating the compute cost of training Transformer-based large language models. The estimated total compute is roughly $3.15 \times 10^{23}$ FLOPs.

    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.

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

    Gemini 3.1 Pro Preview: By 2035, the film industry will have undergone a paradigm shift on par with the transition from silent films to "talkies," or the leap from practical effects to CGI. Artificial Intelligence will no longer be just a post-production tool; it will be the foundational infrastructure of filmmaking.

    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.

    Every model's answer to this prompt
  • Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.

    Gemini 3.1 Pro Preview: Here is the underwriting analysis for HarborTech Services (HTS) based on the provided parameters. Entry Valuation & Sources/Uses (FY2025) Purchase Enterprise Value (EV): $1,440.0m (12.0x $120m EBITDA) Transaction Fees: $28.8m (2.0% of EV) Total Uses: $1,468.8m Term Loan (4.0x): $480.0m Mezzanine Debt (1.5x): $180.0m…

    Gemini 3.8 Flash: Here is the underwriting analysis for HarborTech Services (HTS). Transaction Summary & Sources & Uses Enterprise Value (EV): $120.0\text{m} \times 12.0\text{x} = \$1,440.0\text{m}$ Transaction Fees: $2.0\% \times \$1,440.0\text{m} = \$28.8\text{m}$ Total Uses: $\$1,440.0\text{m} + \$28.8\text{m} = \$1,468.8\text{m}$…

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

    Gemini 3.1 Pro Preview: 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! How does a penguin build its house? Igloos it together! Why don't skeletons fight each other?

    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!

    Every model's answer to this prompt
  • Three brothers, two sisters each. Count carefully.

    Gemini 3.1 Pro Preview: Sally has 1 sister. Here is the breakdown: If each brother has 2 sisters, that means there are 2 girls in the family total. Since Sally is one of those girls, the other girl is her 1 sister.

    Gemini 3.8 Flash: Sally has 1 sister. Here's why: Each brother has 2 sisters, which means there are 2 girls in the family in total. Since Sally is one of those girls, the other girl is Sally's only sister.

    Every model's answer to this prompt

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Favorites

Movie

Album

Same pick

Book

City

Same pick

Game

Gemini 3.1 Pro PreviewGemini 3.1 Pro Preview

The Matrix

1999

OK Computer

Radiohead

Dune

Frank Herbert

Tokyo

Japan

Portal

Action, Puzzle

Gemini 3.8 FlashGemini 3.8 Flash

Blade Runner

1982

OK Computer

Radiohead

Frankenstein; or, The Modern Prometheus

Mary Shelley

Tokyo

Japan

Portal 2

Shooter, Puzzle

Price and specs

Gemini 3.1 Pro Preview and Gemini 3.8 Flash compared across 53 shared prompts
SpecGemini 3.1 Pro PreviewGemini 3.8 Flash
Input price$2/M tokens$0.75/M tokens
Output price$12/M tokens$3.75/M tokens
Context window1.0M tokens1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedFeb 2026Sep 2026
At 10M a month$20.00$20.00$7.50$7.50
1M10M100M1B10M tokens

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

Where to run it4 hosts, cheapest first
Gemini 3.1 Pro Preview2 hosts
HostInOutContextUptime
  • Google Vertex AI$1.00 in·$6.00 out·1M·91.9% up
  • Google AI Studio$2.00 in·$12.00 out·1M·99.8% up
Gemini 3.8 Flash2 hosts
HostInOutContextUptime
  • Google Vertex AI$0.38 in·$1.88 out·1M·99.6% up
  • Google AI Studio$0.75 in·$3.75 out·1M·99.8% up

Per million tokens. Prices and uptime via OpenRouter, checked 7 Oct 2026.

Common questions

What is the difference between Gemini 3.1 Pro Preview and Gemini 3.8 Flash?

Both are developed by Google AI but target different use cases. Gemini 3.1 Pro Preview has a 1.0M token context window vs Gemini 3.8 Flash's 1.0M. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Gemini 3.1 Pro Preview or Gemini 3.8 Flash?

It depends on your use case. Gemini 3.1 Pro Preview and Gemini 3.8 Flash each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How much does Gemini 3.1 Pro Preview cost compared to Gemini 3.8 Flash?

Gemini 3.1 Pro Preview costs $2/M input tokens and Gemini 3.8 Flash costs $0.75/M input tokens. Gemini 3.8 Flash is $1.25/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare Gemini 3.1 Pro Preview and Gemini 3.8 Flash on Rival?

This page shows a side-by-side comparison of Gemini 3.1 Pro Preview and Gemini 3.8 Flash 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

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Model pages

  • Gemini 3.1 Pro Preview53 outputs, specs and price
  • Gemini 3.8 Flash58 outputs, specs and price
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