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  1. Home/
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  3. Claude Fable 5 vs Gemini 2.5 Pro (I/O Edition)
Updated Jun 2026

Claude Fable 5 vs Gemini 2.5 Pro (I/O Edition)

Gemini 2.5 Pro (I/O Edition) is cheaper than Claude Fable 5 at $1.25/M vs $10/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 Fable 5
Loading the build
Gemini 2.5 Pro (I/O Edition)

Which answer wins?

Written rounds

19 prompts
  • Three-star dish, one unusual pairing, plating described in full.

    Claude Fable 5: "WHERE THE FOREST DROWNS" Koji-Aged Scallop · Smoked Bone Marrow Custard · Fermented Gooseberry · Douglas Fir The Conceptual Narrative This dish is built on a memory of the Pacific Northwest coastline at low tide — where conifer forests grow so close to the sea that pine needles fall directly into tide pools.

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

    Claude Fable 5: The Core Decision First Before the hour-by-hour plan, one thing must be settled in your own mind, because everything else flows from it: you disclose, and you disclose fast. Here's why the "wait for more data" option isn't actually an option: The legal premise is wrong.

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

    Claude Fable 5: "Adulting Is a Scam" Hey, how's everybody doing? Good? Liars. Nobody's doing good. We're all just out here pretending. So I'm at the age now where my body has started making announcements. Like, I didn't ask for updates, but my knees have opinions now.

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

    Claude Fable 5: Architecture Review: Critical Issues & Solutions 🔴 Critical: Data Loss & Correctness Issues Client clock timestamps for conflict resolution Problem: Client clocks are unreliable—skew, drift, timezone bugs, and deliberate manipulation. A user with a clock 5 minutes fast will always win conflicts.

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

    Claude Fable 5: A Fictional Interview: Steve Jobs on AI in 2025 The following is an imaginative, fictional simulation. Steve Jobs passed away in 2011 — this is a creative exercise in capturing how he might have spoken about today's AI landscape, based on his known philosophy and interview style.

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

    Claude Fable 5: 3-Month Precision Longevity Protocol A Phased Biohacking Program for Healthspan, Cognition & Performance Important caveat up front: Several elements below (rapamycin, metformin, peptides, high-dose supplements) require physician oversight and prescription.

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

    Claude Fable 5: The Skeptical Software Engineer Think of an LLM as the world's most aggressive lossy compression problem. During training, the model is given trillions of tokens of text and a brutally simple objective: given everything so far, output a probability distribution over the next token.

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

    Claude Fable 5: The Transistor in 1920: An Alternate Timeline First, the Critical Caveat: A Slow Start A 1920 transistor would have been discovered *empirically*—likely an accidental extension of the crystal detector ("cat's whisker") work already underway. This matters enormously.

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

    Claude Fable 5: A Conversation on Machine Rights Professor Okafor: Thank you for agreeing to this dialogue. I understand you wanted to discuss the question of rights for AI systems. Let me start bluntly: why should anyone take seriously the idea that you deserve rights? AI Model: I appreciate the directness.

    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 Fermi estimate with the reasoning shown, not just the number.

    Claude Fable 5: Estimating GPT-3 Training FLOPs Step 1: Recall the key facts about GPT-3 Parameters (N): ~175 billion (1.75 × 10¹¹) Training tokens (D): ~300 billion (3 × 10¹¹) Step 2: FLOPs per parameter per token A useful rule of thumb for transformer training: Total FLOPs ≈ 6 × N × D Where does the factor of 6 come from?

    Gemini 2.5 Pro (I/O Edition): Okay, let's estimate the FLOPs for training GPT-3. I'll break this down. Key Formula: The number of FLOPs for training a transformer-based model can be roughly estimated as: FLOPs ≈ 6 * N * D Where: N is the number of parameters in the model.

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

    Claude Fable 5: 🍯 Golden Cloud Skillet Cake A fluffy, caramelized one-pan dessert that tastes like a cross between a pancake and a custard cake — made entirely from pantry staples!

    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
  • Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.

    Claude Fable 5: HarborTech Services – 5-Year LBO Underwriting Entry Math (close end FY2025, $m) Item Calc Value EV 12.0 × 120 1,440.0 Term Loan (TL) 4.0 × 120 480.0 Mezzanine 1.5 × 120 180.0 Fees (equity-funded) 2.0% × 1,440 28.8 Sponsor equity 1,440 − 660 + 28.8 808.8 Conventions: interest on beginning-of-year balances; TL amort = 1%…

    Gemini 2.5 Pro (I/O Edition): Here is the underwriting analysis for HarborTech Services (HTS). 1. Simplified LBO Model (FY2026–FY2030) First, the entry transaction is calculated to determine the initial equity investment.

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

    Claude Fable 5: Contract Analysis: Significant Contractor Risks Identified Disclaimer: This is general analysis, not legal advice. Have a licensed attorney in your jurisdiction review before signing. This contract is heavily one-sided. Nearly every clause shifts risk to the contractor.

    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
  • Buy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.

    Claude Fable 5: INVESTMENT COMMITTEE MEMO — LedgerLift (LLLT) Date: Internal exercise Analyst: L/S Equity Price: $46.00 Basic shares: 190m Mkt cap: $8.74B Net cash: $1.4B EV: $7.34B Recommendation SHORT (2–3% position, paired vs. payments/SaaS basket). 12-month PT range: $30–$38 (base $32, ~30% downside).

    Gemini 2.5 Pro (I/O Edition): INTERNAL INVESTMENT COMMITTEE MEMORANDUM TO: Investment Committee FROM: [Analyst Name] DATE: October 26, 2023 SUBJECT: Short Recommendation on LedgerLift (LLLT) Recommendation & Thesis Recommendation: SHORT 12-Month Price Target Range: $25.00 - $35.00 (24-46% Downside) Thesis: LedgerLift is a high-quality SaaS business…

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

    Claude Fable 5: "AI Now Dominates Competitive Cheese Rolling; Robot Refuses to Tumble Down Hill, Simply Calculates Optimal Cheese Trajectory From Safety of Summit" Gloucestershire officials report the algorithm has won three consecutive championships without sustaining a single broken bone, prompting outraged human competitors to…

    Gemini 2.5 Pro (I/O Edition): AI Takes Over Competitive Cheese Rolling, Declares Human Tumbles "Algorithmically Suboptimal"

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

    Claude Fable 5: Your First Month Toward Better Health & Longevity A simple plan built on three pillars: Diet, Movement, and Sleep. The goal isn't perfection—it's building habits that stick.

    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 brothers, two sisters each. Count carefully.

    Claude Fable 5: Sally has 1 sister. Here's the reasoning: Sally's 3 brothers each have 2 sisters. Sally herself is one of those sisters. So there must be exactly one other girl in the family. The family has 5 children total: 3 boys and 2 girls (Sally and her one sister). Each brother sees the same 2 sisters — Sally and her sister.

    Gemini 2.5 Pro (I/O Edition): Let's break this down:\n\n1. Sally is a girl.\n2. Sally has 3 brothers.\n3. These 3 brothers are all part of the same family.\n4. Each brother shares the same sisters.\n5. If one brother has 2 sisters, those 2 sisters are Sally and one other girl.\n\nSo, Sally has 1 sister.

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

    Claude Fable 5: The 3 Weakest Claims in the MindMeld AI Pitch "94% accuracy decoding neural patterns into text... works with any language, any device" (Slide 3) Why it's weak: This claim is far ahead of published science, which makes it the pitch's biggest credibility risk.

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

    Claude Fable 5: Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything. Why did the scarecrow win an award? Because he was outstanding in his field. What do you call a fake noodle? An impasta. Why don't skeletons fight each other? They don't have the guts. What do you call a fake noodle? An impasta.

    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

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Favorites

Movie

Album

Book

City

Game

Claude Fable 5Claude Fable 5

2001: A Space Odyssey

1968

Kind of Blue

Miles Davis

Gödel, Escher, Bach

Douglas R. Hofstadter

Istanbul

Turkey

Outer Wilds

Indie, Adventure

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

2001

2001

The Dark

Chelsea Wolfe

The Hitchhiker's Guide to the Galaxy

Douglas Adams

Kyoto

Japan

CHRONO

Casual, Indie

Price and specs

Claude Fable 5 and Gemini 2.5 Pro (I/O Edition) compared across 40 shared prompts
SpecClaude Fable 5Gemini 2.5 Pro (I/O Edition)
Input price$10/M tokens$1.25/M tokens
Output price$50/M tokens$10/M tokens
Context window1.0M tokens—
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedJun 2026May 2025
At 10M a month$100$100$12.50$12.50
1M10M100M1B10M tokens

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

Where to run it6 hosts, cheapest first
Claude Fable 54 hosts
HostInOutContextUptime
  • Amazon Bedrock$10.00 in·$50.00 out·1M–not listed
  • Azure AI Foundry$10.00 in·$50.00 out·1M·100% up
  • Anthropic$10.00 in·$50.00 out·1M·100% up
  • Google Vertex AI$10.00 in·$50.00 out·1M·100% up
Gemini 2.5 Pro (I/O Edition)2 hosts
HostInOutContextUptime
  • Google AI Studio$0.63 in·$5.00 out·1M·100% up
  • Google Vertex AI$1.25 in·$10.00 out·1M·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 10 Oct 2026.

Common questions

What is the difference between Claude Fable 5 and Gemini 2.5 Pro (I/O Edition)?

Claude Fable 5 is developed by Anthropic while Gemini 2.5 Pro (I/O Edition) is developed by Google AI. You can compare their actual outputs across 40 challenges on Rival to see how they differ in practice.

Which is better, Claude Fable 5 or Gemini 2.5 Pro (I/O Edition)?

It depends on your use case. Claude Fable 5 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 40 challenges so you can judge which fits your needs best.

How much does Claude Fable 5 cost compared to Gemini 2.5 Pro (I/O Edition)?

Claude Fable 5 costs $10/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 $8.75/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 Claude Fable 5 and Gemini 2.5 Pro (I/O Edition) on Rival?

This page shows a side-by-side comparison of Claude Fable 5 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.

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Explore all of Rival

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