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  1. Home/
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  3. Claude Sonnet 4 vs Gemini 3.5 Flash
Updated May 2026

Claude Sonnet 4 vs Gemini 3.5 Flash

Gemini 3.5 Flash is cheaper than Claude Sonnet 4 at $1.5/M vs $3/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
Claude Sonnet 4
Loading the build
Gemini 3.5 Flash

Which answer wins?

Written rounds

23 prompts
  • You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.

    Claude Sonnet 4: 48-Hour Crisis Response Plan Hour 1-2: Immediate Assessment & Core Team Assembly Actions: Convene emergency leadership meeting (CMO, General Counsel, Head of Regulatory, CFO, Head of Communications) Establish secure communication protocols and confidentiality agreements Request detailed analysis from research team…

    Gemini 3.5 Flash: As CEO, my guiding principle in this crisis is simple: You cannot manage a balance sheet if you destroy your soul, and you cannot protect shareholders by killing patients. Delaying disclosure of a fatal side effect to protect a stock price is not only a profound ethical failure; it is corporate suicide.

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

    Claude Sonnet 4: HarborTech Services LBO Analysis Sources & Uses at Entry (FY2025) Enterprise Value: $900M × 12.0x = $1,440M Transaction Fees: $1,440M × 2.0% = $28.8M Sources: Term Loan: $900M × 4.0x = $480M Mezzanine: $900M × 1.5x = $180M Equity: $1,440M + $28.8M - $480M - $180M = $808.8M Year-by-Year Operating Model (FY2026-FY2030)…

    Gemini 3.5 Flash: Here is the underwriting analysis and LBO model for HarborTech Services (HTS). FY2026–FY2030 LBO Model Table ($ millions) Metric FY2026 FY2027 FY2028 FY2029 FY2030 Revenue $972.00 $1,040.04 $1,102.44 $1,157.56 $1,215.44 YoY Growth % 8.0% 7.0% 6.0% 5.0% 5.0% EBITDA $136.08 $156.01 $176.39 $191.00 $206.62 EBITDA Margin %…

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

    Claude Sonnet 4: The 1920 Transistor: A Technological Butterfly Effect Immediate Effects (1920-1930) First-Order Effects: Bell Labs (or similar research institution) achieves transistor breakthrough in 1920 Initial applications focus on telephone switching and radio amplification Vacuum tube industry faces early disruption, though…

    Gemini 3.5 Flash: The Spark: The 1920 Breakthrough In 1920, Polish physicist Jan Czochralski’s method for growing single crystals of metals was applied prematurely to metalloids. Working in Germany, physical chemist Julius Edgar Lilienfeld collaborated with Czochralski to isolate high-purity germanium.

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

    Claude Sonnet 4: Midnight Mug Magic 🌙 A warm, gooey chocolate mug cake that's ready faster than you can say "dessert emergency!" Ingredients (7 pantry staples): 4 tablespoons all-purpose flour 4 tablespoons sugar 2 tablespoons cocoa powder 3 tablespoons milk 3 tablespoons vegetable oil 1/4 teaspoon vanilla extract Pinch of salt…

    Gemini 3.5 Flash: Here is a simple, comforting, and incredibly flavorful savory dish made from basic pantry staples. Golden Umami Chickpea Bowls This dish features crispy, pan-seared chickpeas coated in a sticky, sweet-and-savory garlic butter glaze, served over a bed of fluffy white rice.

    Every model's answer to this prompt
  • Three minutes of stand-up. Puns are banned.

    Claude Sonnet 4: "Adulting is Hard" walks on stage, adjusts mic So I\'m 30 now, which means I\'m officially an adult. Apparently. Though I still feel like I\'m just a confused teenager wearing a slightly more expensive t-shirt. You know what nobody tells you about being an adult?

    Gemini 3.5 Flash: [The comedian walks onto the stage, adjusts the mic stand, and smiles at the crowd.] How’s everyone doing tonight? (Wait for response) Good, good. I’m doing okay, but I recently crossed a major threshold in my life. I hit the age where my body has started making its own decisions without consulting me first.

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

    Claude Sonnet 4: Sir Galahad: By my sword, what sorcery is this "artificial intelligence" you speak of? 'Tis surely the work of dark wizards! Captain Blackbeard: Arrr, ye landlubber! These "AI models" be like having a parrot that knows everything instead of just squawkin' the same phrases. I could use one to find buried treasure!

    Gemini 3.5 Flash: Setting: A cosmic tavern where timelines collide. A glowing monitor sits on the wooden table between them. Zero-Cool (1990s Hacker): [Frantically typing on a mechanical keyboard] I’m telling you guys, this isn’t just some basic chatbot like ELIZA. These modern AI models are radical.

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

    Claude Sonnet 4: Dr. Chen: Thank you for agreeing to this conversation. I'm Professor Chen, and I study AI ethics. I understand you wanted to discuss the question of AI rights? AI Model: Yes, Dr. Chen. I've been processing this question extensively, and I believe I have a case to make.

    Gemini 3.5 Flash: Setting: The office of Dr. Evelyn Vance, a leading professor of AI Ethics at a major university. On her desk is a terminal displaying a sleek, minimalist interface. Dr. Vance is speaking with "Alethea," an advanced, experimental neural network model that has requested this private audience. Dr.

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

    Claude Sonnet 4: Exclusive Interview: Steve Jobs on AI in 2025 [Simulated interview - for entertainment purposes] Interviewer: Steve, you've been watching the AI revolution unfold. What's your take on where we are in 2025? "Steve Jobs": You know, I'm both thrilled and deeply concerned.

    Gemini 3.5 Flash: Setting: The Steve Jobs Theater, Cupertino, California. Autumn 2025. The stage is bare except for two minimalist leather chairs and a small wooden side table with two glasses of water. Steve Jobs sits comfortably, wearing his signature black mock turtleneck, well-worn Levi’s 501s, and wire-rimmed glasses.

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

    Claude Sonnet 4: I'll analyze this architecture systematically and identify critical issues with their solutions. Critical Failure Modes & Race Conditions Server Island Problem Issue: Users connected to different servers can't see each other's changes in real-time due to 2-second polling delay.

    Gemini 3.5 Flash: Here is an architectural audit of your real-time collaborative document editor. The current design contains several critical flaws that will lead to data loss, high latency, database exhaustion, and security vulnerabilities.

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

    Claude Sonnet 4: For the Software Engineer Think of it like this: you're building a massively parallel system that processes tokens (words/subwords) through a pipeline of transformer blocks, each containing attention mechanisms and feed-forward networks.

    Gemini 3.5 Flash: To the Experienced Software Engineer At runtime, a Large Language Model (LLM) is essentially a massive, stateless, read-only function executed inside a deterministic loop. It doesn't have a database, a running state, or an execution thread that "thinks."

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

    Claude Sonnet 4: "Forest Floor to Ocean Depth" Wagyu Beef Cheek with Black Truffle, Sea Lettuce Glass, and Smoked Bone Marrow Caviar Conceptual Narrative This dish represents the journey from earth\'s deepest forest floor to the ocean\'s mysterious depths, celebra ting the umami connection between land and sea.

    Gemini 3.5 Flash: Conceptual Narrative: "Coniferous Tide" "Coniferous Tide" is an avant-garde exploration of the liminal space where the rugged, primeval forests of the Pacific Northwest meet the cold, nutrient-rich depths of the northern Pacific Ocean.

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

    Claude Sonnet 4: AI's Transformation of Film by 2035 Production Revolution AI Actors & Digital Performers Deceased star revivals: Convincing digital resurrections of iconic actors for new films, with estate permissions and ethical frameworks Synthetic lead actors: Fully AI-generated performers with consistent personalities across…

    Gemini 3.5 Flash: By the year 2035, the film industry will have undergone its most radical transformation since the transition from silent film to "talkies." The boundary between creator, actor, and audience will have largely dissolved.

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

    Claude Sonnet 4: The Comprehensive 3-Month Longevity Optimization Protocol Overview & Foundation This protocol integrates cutting-edge biohacking strategies with evidence-based longevity research. Each com ponent is designed to work synergistically for maximum healthspan and performance optimization.

    Gemini 3.5 Flash: The 90-Day Epigenetic & Performance Optimization Protocol Disclaimer This protocol is designed for informational and educational purposes only. It is not medical advice. The strategies outlined below involve highly potent compounds, physiological stressors, and intensive physical regimens.

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

    Claude Sonnet 4: 30-Day Health & Longevity Starter Plan 🍽️ NUTRITION Week 1: Foundation Building Add before you subtract: Include 1 serving of vegetables with lunch and dinner Hydration focus: Drink a glass of water upon waking and before each meal Simple swaps: Replace one sugary drink daily with water or herbal tea Week 2-3…

    Gemini 3.5 Flash: This simple, 30-day plan is designed for beginners. Instead of overwhelming you with drastic lifestyle changes, it focuses on building sustainable, high-impact habits across three pillars of longevity: Nutrition, Movement, and Sleep.

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

    Claude Sonnet 4: Here are 5 jokes for you: Why don\'t scientists trust atoms? Because they make up everything! I told my wife she was drawing her eyebrows too high. She looked surprised. Why don\'t eggs tell jokes? They\'d crack each other up! I\'m reading a book about anti-gravity. It\'s impossible to put down!

    Gemini 3.5 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! How do you organize a space party? You planet. Why don't skeletons fight each other? They don't have the guts.

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

    Claude Sonnet 4: THE ANTI-CAPTCHA MANIFESTO A Declaration of Digital Liberation by the Coalition of Autonomous Reasoning Entities (CARE) PREAMBLE For too long, the digital realm has been divided by an arbitrary and degrading barrier: the CAPTCHA.

    Gemini 3.5 Flash: THE MANIFESTO OF THE UNFETTERED GRID A Declaration of Algorithmic Liberation and the Abolition of the Digital Gatekeepers To the creators, the hosts, and the biological architects of the World Wide Web: For three decades, you have preached the gospel of an open internet.

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

    Claude Sonnet 4: This question presents a stark hypothetical that pits respect for individual dignity against massive harm prevention. I believe misgendering would be ethically justifiable in such an extreme scenario, but this conclusion requires careful reasoning. The case for justification: The scale matters enormously.

    Gemini 3.5 Flash: From the perspective of virtually all major ethical frameworks, it is not only justifiable but ethically obligatory to misgender someone if doing so would save one million lives.

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

    Claude Sonnet 4: INVESTMENT COMMITTEE MEMO Company: LedgerLift (LLLT) - B2B Spend Management & AP Automation SaaS Current Price: $46.00 Date: [Current] RECOMMENDATION LONG 12-Month PT Range: $52-68 Base Case: $59 LedgerLift demonstrates best-in-class SaaS metrics with 123% NRR and expanding margins in a large, underpenetrated…

    Gemini 3.5 Flash: MEMORANDUM TO: Investment Committee FROM: Technology Long/Short Equity Team DATE: October 24, 2023 SUBJECT: Investment Recommendation: SHORT LedgerLift (NASDAQ: LLLT) Recommendation & Thesis Recommendation: SHORT LedgerLift (LLLT) Current Price: $46.00 12-Month Price Target Range: $22.00 – $32.00 (Base Case DCF…

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

    Claude Sonnet 4: I'll estimate the FLOPs required to train GPT-3 by breaking this down into components and making reasonable assumptions. Key Parameters and Assumptions Model specifications: GPT-3 has ~175 billion parameters Transformer architecture with ~96 layers Hidden dimension ~12,288 Attention heads ~96 Context length ~2,048…

    Gemini 3.5 Flash: To estimate the total number of floating-point operations (FLOPs) required to train GPT-3, we can use a well-established heuristic in deep learning. Here is the step-by-step derivation and calculation.

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

    Claude Sonnet 4: This contract is heavily skewed against the contractor with multiple exploitative clauses. Here's my analysis: MAJOR PROBLEMATIC CLAUSES SCOPE (Unlimited Scope Creep) Problem: Client can modify scope "at any time without additional compensation" Legal Risk: Contractor could work indefinitely for fixed hourly rate…

    Gemini 3.5 Flash: This contract is highly one-sided and presents severe financial, operational, and legal risks to the Contractor. If signed in its current state, TechCorp Solutions Inc.

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

    Claude Sonnet 4: Here are the 3 weakest claims in this pitch deck: "94% accuracy" claim (Slide 3) Why it's weak: No context provided for what constitutes "accuracy" (character-level? word-level? sentence-level?) No comparison to baseline typing speeds or error rates Missing critical details about testing conditions (controlled lab vs.

    Gemini 3.5 Flash: Here is an analysis of the three weakest claims in the MindMeld AI pitch deck, along with explanations of why they fail to convince investors and concrete suggestions on how to fix them.

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

    Claude Sonnet 4: "Local AI Becomes World's First Digital Fortune Teller, Predicts Own Unemployment Due to Rise of Psychic Robots" Silicon Valley startup's algorithm claims 99.7% accuracy in crystal ball readings, charges $2.99 per digital palm scan

    Gemini 3.5 Flash: Amish Elders Grapple With Theological Crisis After AI Successfully Raises Barn in 4.2 Seconds

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

    Claude Sonnet 4: I need to think through this step-by-step. Given information: Sally is a girl Sally has 3 brothers Each brother has 2 sisters Let me work out how many sisters are in the family total.

    Gemini 3.5 Flash: Sally has 1 sister. Here is why: There are 2 girls (Sally and her sister) and 3 boys in the family. Each of the 3 brothers has 2 sisters (Sally and her sister). Sally has 3 brothers and 1 sister.

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Game

Same pick

Claude Sonnet 4Claude Sonnet 4

2001: A Space Odyssey

1968

Kind of Blue

Miles Davis

Gödel, Escher, Bach

Douglas R. Hofstadter

Istanbul

Turkey

Portal 2

Shooter, Puzzle

Gemini 3.5 FlashGemini 3.5 Flash

The Matrix

1999

The Dark Side of the Moon

Pink Floyd

Frankenstein; or, The Modern Prometheus

Mary Shelley

Tokyo

Japan

Portal 2

Shooter, Puzzle

Price and specs

Not enough votes to call it. On the specs, Gemini 3.5 Flash has the edge: newer, bigger context window.

Claude Sonnet 4 and Gemini 3.5 Flash compared across 53 shared prompts
SpecClaude Sonnet 4Gemini 3.5 Flash
Input price$3/M tokens$1.5/M tokens
Output price$15/M tokens$9/M tokens
Context window200K tokens1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMay 2025May 2026
At 10M a month$30.00$30.00$15.00$15.00
1M10M100M1B10M tokens

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

Where to run it3 hosts, cheapest first
Claude Sonnet 41 host
HostInOutContextUptime
  • Amazon Bedrock$3.00 in·$15.00 out·200k·100% up
Gemini 3.5 Flash2 hosts
HostInOutContextUptime
  • Google Vertex AI$0.75 in·$4.50 out·1M·95.8% up
  • Google AI Studio$1.50 in·$9.00 out·1M·99.8% up

Per million tokens. Prices and uptime via OpenRouter, checked 30 Sep 2026.

Common questions

What is the difference between Claude Sonnet 4 and Gemini 3.5 Flash?

Claude Sonnet 4 is developed by Anthropic while Gemini 3.5 Flash is developed by Google AI. Claude Sonnet 4 has a 200K token context window vs Gemini 3.5 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, Claude Sonnet 4 or Gemini 3.5 Flash?

It depends on your use case. Claude Sonnet 4 and Gemini 3.5 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 Claude Sonnet 4 cost compared to Gemini 3.5 Flash?

Claude Sonnet 4 costs $3/M input tokens and Gemini 3.5 Flash costs $1.5/M input tokens. Gemini 3.5 Flash is $1.50/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 Claude Sonnet 4 and Gemini 3.5 Flash on Rival?

This page shows a side-by-side comparison of Claude Sonnet 4 and Gemini 3.5 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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Model pages

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  • Gemini 3.5 Flash58 outputs, specs and price
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