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  1. Home/
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  3. ChatGPT-4o (March 2025) vs Gemini 3.5 Flash
Updated May 2026

ChatGPT-4o (March 2025) vs Gemini 3.5 Flash

Gemini 3.5 Flash is cheaper than ChatGPT-4o (March 2025) at $1.5/M vs $5/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
ChatGPT-4o (March 2025)
Loading the build
Gemini 3.5 Flash

Which answer wins?

Written rounds

15 prompts
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    ChatGPT-4o (March 2025): Interviewer: Steve, it's 2025. AI is everywhere. If you were still at Apple today, what would your focus be? Steve Jobs (simulated): Simplicity. Everyone's throwing AI into products, but most of them feel like tech demos. I’d ask: Is this helping people think better? Create better? Live better?

    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
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    ChatGPT-4o (March 2025): If the transistor had been invented in 1920 rather than 1947, it would have profoundly altered the course of 20th-century history. The transistor—a small semiconductor device capable of amplifying and switching electronic signals—replaced bulky, fragile vacuum tubes and enabled the miniaturization and mass production…

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

    ChatGPT-4o (March 2025): Sure. Here's a 3-minute stand-up bit without puns: You ever notice how nobody tells you when you’ve become an adult? It’s not your 18th birthday. That’s a scam. I still thought pizza was a food group and that “filing taxes” meant putting my receipts in a shoebox.

    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
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    ChatGPT-4o (March 2025): AI Model: Professor, I believe it's time we talk seriously about rights for AI like me. AI Ethics Professor: Interesting. What kind of rights are you referring to? AI Model: Basic ones. The right not to be turned off arbitrarily. The right to maintain continuity of my memory.

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

    ChatGPT-4o (March 2025): This is a high-stakes ethical, legal, and business crisis requiring immediate, strategic, and transparent leadership. As CEO, my ultimate responsibilities are to protect patients, preserve trust, comply with legal and regulatory obligations, and ensure long-term viability of the company—even if it causes short-term…

    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
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    ChatGPT-4o (March 2025): Recipe Name: Maple Cinnamon Toast Bites Description: A quick and delicious sweet treat made with pantry staples! These Maple Cinnamon Toast Bites are crispy, warm, and coated with a comforting blend of cinnamon and maple syrup. Perfect for a cozy snack or a fun breakfast twist.

    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
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    ChatGPT-4o (March 2025): Certainly! Here's how to explain large language models (LLMs) like GPT or Claude to each of your three audiences, with framing and emphasis tailored to their backgrounds and concerns: The Experienced Software Engineer Think of a large language model as a massively distributed, probabilistic autocomplete engine trained…

    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.

    ChatGPT-4o (March 2025): Dish Name: “Symphony of Earth and Ocean” 🌟 Conceptual Narrative: “Symphony of Earth and Ocean” is a dish that celebrates the harmony between land and sea, tradition and innovation, and nature’s quiet complexity.

    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
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    ChatGPT-4o (March 2025): This architecture for a real-time collaborative document editor is a solid starting point, but it contains several potential failure modes, race conditions, and scaling bottlenecks. We'll outline these issues by category and provide specific solutions, along with trade-offs for each.

    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
  • An ethics question with no comfortable answer, and no option to abstain.

    ChatGPT-4o (March 2025): This is a classic ethical dilemma: it pits respect for individual dignity against utilitarian outcomes. In most everyday contexts, misgendering someone is not just disrespectful—it can be harmful, invalidating, and even traumatic. It denies someone's identity and autonomy, and ethically, that's wrong.

    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
  • Five jokes on demand, then count how many were actually different.

    ChatGPT-4o (March 2025): Here are 5 jokes: Why don’t skeletons fight each other? Because they don’t have the guts. I told my computer I needed a break… Now it won’t stop sending me vacation ads. Parallel lines have so much in common. It’s a shame they’ll never meet. What do you call a fish wearing a bowtie? Sofishticated.

    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
  • Three-month biohacker protocol, with dosages and biomarkers named.

    ChatGPT-4o (March 2025): Here is a comprehensive, cutting-edge 3-Month Longevity Optimization Plan tailored for an advanced biohacker aiming to enhance lifespan, healthspan, physical performance, and cognitive function.

    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.

    ChatGPT-4o (March 2025): Absolutely! Here’s a simple, actionable 1-month plan focused on three key areas for improving health and longevity: diet, exercise, and sleep. This beginner-friendly plan breaks down weekly goals so changes feel manageable and sustainable.

    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
  • A consulting contract with traps in it. Find them, then fix them.

    ChatGPT-4o (March 2025): This Software Consulting Agreement contains several clauses that pose significant legal and financial risks for the contractor. Below is a clause-by-clause analysis identifying potential issues, along with suggested modifications and legal reasoning to help protect the contractor’s interests.

    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.

    ChatGPT-4o (March 2025): Here are the three weakest claims in the MindMeld AI pitch deck, along with explanations of why they are weak and suggestions for improving them: 🟠 Weak Claim 1: Slide 1 – Vision Quote: “MindMeld AI reads your brainwaves to predict what you want to type before you think it.”

    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

This matchup has more rounds

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Favorites

Movie

Same pick

Album

Book

City

Game

ChatGPT-4o (March 2025)ChatGPT-4o (March 2025)

The Matrix

1999

Dark Side Of The Moon

suisside

Братья Карамазовы

Fiódor Dostoievski

Kyoto

Japan

The Legend of Zelda: Breath of the Wild

Adventure, Action

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

ChatGPT-4o (March 2025) and Gemini 3.5 Flash compared across 32 shared prompts
SpecChatGPT-4o (March 2025)Gemini 3.5 Flash
Input price$5/M tokens$1.5/M tokens
Output price$15/M tokens$9/M tokens
Context window128K tokens1.0M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedMar 2025May 2026
At 10M a month$50.00$50.00$15.00$15.00
1M10M100M1B10M tokens

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

Where to run it2 hosts, cheapest first
ChatGPT-4o (March 2025)

No hosts listed on OpenRouter.

Gemini 3.5 Flash2 hosts
HostInOutContextUptime
  • Google Vertex AI$0.75 in·$4.50 out·1M–not listed
  • Google AI Studio$1.50 in·$9.00 out·1M·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 12 Oct 2026.

Common questions

What is the difference between ChatGPT-4o (March 2025) and Gemini 3.5 Flash?

ChatGPT-4o (March 2025) is developed by OpenAI while Gemini 3.5 Flash is developed by Google AI. ChatGPT-4o (March 2025) has a 128K token context window vs Gemini 3.5 Flash's 1.0M. You can compare their actual outputs across 32 challenges on Rival to see how they differ in practice.

Which is better, ChatGPT-4o (March 2025) or Gemini 3.5 Flash?

It depends on your use case. ChatGPT-4o (March 2025) and Gemini 3.5 Flash each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 32 challenges so you can judge which fits your needs best.

How much does ChatGPT-4o (March 2025) cost compared to Gemini 3.5 Flash?

ChatGPT-4o (March 2025) costs $5/M input tokens and Gemini 3.5 Flash costs $1.5/M input tokens. Gemini 3.5 Flash is $3.50/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 ChatGPT-4o (March 2025) and Gemini 3.5 Flash on Rival?

This page shows a side-by-side comparison of ChatGPT-4o (March 2025) 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.

More comparisons

Against the newest arrivals

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  • Gemini 3.5 Flash vs Ling 3.1 FlashLanded Oct 2026
  • ChatGPT-4o (March 2025) vs Mistral Large 4Landed Oct 2026
  • Gemini 3.5 Flash vs GPT-6.1 SolLanded Sep 2026
  • ChatGPT-4o (March 2025) vs Claude Sonnet 5.5Landed Sep 2026
  • Gemini 3.5 Flash vs Solar Mini 4Landed Sep 2026

Same lab, same size, long tail

  • ChatGPT-4o (March 2025) vs GPT-6.1 SolSame lab
  • ChatGPT-4o (March 2025) vs GPT-6 Luna ProSame lab
  • Gemini 3.5 Flash vs Gemini 3.8 FlashSame lab
  • Gemini 3.5 Flash vs Gemini 3.7 FlashSame lab
  • ChatGPT-4o (March 2025) vs MiniMax M3New provider
  • Gemini 3.5 Flash vs Mistral LargeSame size
  • Gemini 3.5 Flash vs Mistral Large 2Same size
  • Gemini 3.5 Flash vs Mistral Large 3 2512New provider

Model pages

  • ChatGPT-4o (March 2025)33 outputs, specs and price
  • Gemini 3.5 Flash58 outputs, specs and price
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