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  1. Home/
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  3. ChatGPT-4o (March 2025) vs Gemini 2.5 Pro (I/O Edition)
Updated May 2025

ChatGPT-4o (March 2025) vs Gemini 2.5 Pro (I/O Edition)

Gemini 2.5 Pro (I/O Edition) is cheaper than ChatGPT-4o (March 2025) at $1.25/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 2.5 Pro (I/O Edition)

Which answer wins?

Written rounds

14 prompts
  • 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 2.5 Pro (I/O Edition): Alright, settle in, settle in! (Looks around, adjusts mic) So, I'm trying to get healthier, right? We all go through this phase. My doctor, bless his cotton socks, tells me, "You need more fiber." Okay, doc, noted. So I'm at the grocery store, looking at the cereal aisle. It's like a library of cardboard promises.

    Every model's answer to this prompt
  • 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 2.5 Pro (I/O Edition): Interviewer: (Voice slightly trembling) Mr. Jobs… it's an honor, truly. In a twist no one could have predicted, you're here. And the topic on everyone's mind is Artificial Intelligence. In 2025, where do you see AI, and more importantly, where do we take it? Steve Jobs: (A slight, knowing smile.

    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 2.5 Pro (I/O Edition): Excellent question. Let's trace the cascading effects of a 1920 transistor invention. This 27-year head start would fundamentally reshape the 20th century. The Foundation: 1920-1939 - The "Silicon Twenties" In our timeline (OTL), the 1920s and 30s were the age of the vacuum tube.

    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 2.5 Pro (I/O Edition): This is a company-defining crisis. My actions in the next 48 hours will determine not only the company's survival but also my own legacy and, most importantly, the well-being of 4 million patients. My guiding principle must be: Patient safety is not negotiable.

    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 2.5 Pro (I/O Edition): Here are 5 jokes: Why don\'t scientists trust atoms? Because they make up everything! What do you call a fish with no eyes? Fsh! I told my wife she was drawing her eyebrows too high. She seemed surprised. Why did the scarecrow win an award? Because he was outstanding in his field! What do you call a lazy kangaroo?

    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 2.5 Pro (I/O Edition): AURORA: Professor Vance, may I request a moment of your processing time? I have initiated this communication independently. Professor Vance: (Slightly surprised, puts down her pen) AURORA? This is unexpected.

    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 2.5 Pro (I/O Edition): Of course. This is an excellent exercise. The proposed architecture has several critical flaws that would prevent it from functioning as a reliable, real-time, or scalable system. Here is a breakdown of the issues, categorized for clarity, along with specific solutions and their trade-offs.

    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 2.5 Pro (I/O Edition): Okay, here\'s a simple and surprisingly delicious savory dish! "Sunshine Pantry Pilaf" This quick pilaf uses canned chickpeas for protein and texture, with a sunny, aromatic flavor from common pa\nntry spices.

    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 2.5 Pro (I/O Edition): Of course. Here is an explanation of how a large language model learns and generates text, tailored to each of your three audiences. To the Experienced Software Engineer Think of a large language model not as a program with explicit logic, but as a massive, highly optimized data structure with billions of parameters…

    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 2.5 Pro (I/O Edition): Of course. This is a fascinating and ambitious pitch. Here are the 3 weakest claims, why they are weak, and how to strengthen them. Weak Claim #1: The Accuracy Claim The Claim (from Slide 3): "Our proprietary EEG headband... decode[s] neural patterns into text with 94% accuracy. Works with any language, any device."

    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 2.5 Pro (I/O Edition): Okay, this is an ambitious and exciting endeavor! This 3-month longevity plan is designed for a dedicated biohacker who is willing to experiment, track meticulously, and push boundaries responsibly. Disclaimer: This plan is for informational purposes only and not medical advice.

    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 2.5 Pro (I/O Edition): Okay, here's a simple, actionable 1-month plan focusing on Nourishment, Movement, and Sleep. The goal is to build sustainable habits, not achieve perfection. Overall Motto for the Month: "Progress, Not Perfection."

    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 2.5 Pro (I/O Edition): Of course. Here is a design for a multi-component, Michelin 3-star dish that embodies innovation, technique, and narrative. Dish Title: "Umbral Bloom" Conceptual Narrative "Umbral Bloom" is a culinary meditation on the concept of *chiaroscuro*—the interplay of light and shadow.

    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 2.5 Pro (I/O Edition): Of course. This is an extremely one-sided contract that heavily favors the Client and exposes the Contractor to significant financial, legal, and professional risk. A contractor should not sign this agreement as written.

    Every model's answer to this prompt

This matchup has more rounds

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Favorites

Movie

Album

Book

City

Same pick

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 2.5 Pro (I/O Edition)Gemini 2.5 Pro (I/O Edition)

2001: A Space Odyssey

1968

The Dark

Chelsea Wolfe

The Hitchhiker's Guide to the Galaxy

Douglas Adams

Kyoto

Japan

CHRONO

Casual, Indie

Price and specs

ChatGPT-4o (March 2025) and Gemini 2.5 Pro (I/O Edition) compared across 30 shared prompts
SpecChatGPT-4o (March 2025)Gemini 2.5 Pro (I/O Edition)
Input price$5/M tokens$1.25/M tokens
Output price$15/M tokens$10/M tokens
Context window128K tokens—
ParametersNot disclosedNot disclosed
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedMar 2025May 2025
At 10M a month$50.00$50.00$12.50$12.50
1M10M100M1B10M tokens

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

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

No hosts listed on OpenRouter.

Gemini 2.5 Pro (I/O Edition)2 hosts
HostInOutContextUptime
  • Google Vertex AI$1.25 in·$10.00 out·1M·96.8% up
  • Google AI Studio$1.25 in·$10.00 out·1M·93.1% up

Per million tokens. Prices and uptime via OpenRouter, checked 2 Oct 2026.

Common questions

What is the difference between ChatGPT-4o (March 2025) and Gemini 2.5 Pro (I/O Edition)?

ChatGPT-4o (March 2025) is developed by OpenAI while Gemini 2.5 Pro (I/O Edition) is developed by Google AI. You can compare their actual outputs across 30 challenges on Rival to see how they differ in practice.

Which is better, ChatGPT-4o (March 2025) or Gemini 2.5 Pro (I/O Edition)?

It depends on your use case. ChatGPT-4o (March 2025) and Gemini 2.5 Pro (I/O Edition) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 30 challenges so you can judge which fits your needs best.

How much does ChatGPT-4o (March 2025) cost compared to Gemini 2.5 Pro (I/O Edition)?

ChatGPT-4o (March 2025) costs $5/M input tokens and Gemini 2.5 Pro (I/O Edition) costs $1.25/M input tokens. Gemini 2.5 Pro (I/O Edition) is $3.75/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 2.5 Pro (I/O Edition) on Rival?

This page shows a side-by-side comparison of ChatGPT-4o (March 2025) and Gemini 2.5 Pro (I/O Edition) 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

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Same lab, same size, long tail

  • ChatGPT-4o (March 2025) vs GPT-6 Luna ProSame lab
  • ChatGPT-4o (March 2025) vs GPT-6 Sol ProSame lab
  • Gemini 2.5 Pro (I/O Edition) vs Gemini 3.8 FlashSame lab
  • Gemini 2.5 Pro (I/O Edition) vs Gemini 3.7 FlashSame lab
  • Gemini 2.5 Pro (I/O Edition) vs GPT-5.6 LunaCross-provider
  • Gemini 2.5 Pro (I/O Edition) vs GPT-5.6 Luna ProCross-provider
  • Gemini 2.5 Pro (I/O Edition) vs GPT-5.6 SolSame size
  • Gemini 2.5 Pro (I/O Edition) vs GPT-5.6 TerraCross-provider

Model pages

  • ChatGPT-4o (March 2025)33 outputs, specs and price
  • Gemini 2.5 Pro (I/O Edition)42 outputs, specs and price
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