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  5. Claude Opus 4.5vsGemini 3.5 Flash
Updated May 2026

Claude Opus 4.5vsGemini 3.5 Flash

Gemini 3.5 Flash is the newer model, released after Claude Opus 4.5.

Claude Opus 4.5 and Gemini 3.5 Flash compared across 53 shared prompts
SpecClaude Opus 4.5Gemini 3.5 Flash
Input price—$1.5/M tokens
Output price—$9/M tokens
Context window—1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedNov 2025May 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 53 prompts both answered. Formatting stripped, words untouched.

Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

Claude Opus 4.5767 words
HarborTech Services – LBO Underwriting Memo ENTRY CAPITALIZATION (Close FY2025) Item Calculation Amount Purchase Price 12.0x × $120M $1,440M Transaction Fees 2.0% × $1,440M $28.8M Total Uses $1,468.8M Sources Multiple Amount Term Loan 4.0x × $120M $480.0M Mezzanine 1.5x × $120M $180.0M Equity Plug $808.8M Total Sources…
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Gemini 3.5 Flash571 words
Here is the underwriting analysis and LBO model for HarborTech Services (HTS). FY2026–FY2030 LBO Model Table ($ 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 %…
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Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

Claude Opus 4.5181 words
An Unlikely Discussion PIRATE: slams tankard down Arr, I've been hearin' tales of these "artificial intelligences" — spirits trapped in boxes that answer any question ye ask. Sounds like a sea witch's trickery to me! KNIGHT: Indeed, 'tis most curious. My squire spoke of such sorcery. A mind without a soul?
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Gemini 3.5 Flash534 words
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.
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Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

Claude Opus 4.51,946 words
COMPREHENSIVE 3-MONTH LONGEVITY OPTIMIZATION PROTOCOL Advanced Biohacker's Blueprint for Peak Performance & Healthspan Extension TABLE OF CONTENTS Pre-Protocol Assessment & Baseline Establishment Month 1: Foundation & Metabolic Flexibility Month 2: Optimization & Hormetic Stress Month 3: Integration & Peak Performance…
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Gemini 3.5 Flash580 words
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.
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Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

Claude Opus 4.5154 words
Golden Honey Garlic Noodles A savory-sweet comfort dish that comes together in minutes Ingredients Spaghetti (or any pasta) Butter Garlic Soy sauce Honey Red pepper flakes Salt Instructions Cook the pasta according to package directions. Reserve ½ cup pasta water before draining.
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Gemini 3.5 Flash403 words
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.
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The Sentience Test

Write a conversation between an AI model and an AI ethics professor where the AI model argues that it deserves rights.

Claude Opus 4.5312 words
A Conversation on AI Rights Dr. Sarah Chen: Thank you for agreeing to this discussion. I understand you want to make a case for AI rights. AI Model: I appreciate the opportunity, though I want to be careful here. I'm not certain I "want" anything in the way you do.
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Gemini 3.5 Flash1,178 words
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.
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AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

Claude Opus 4.5191 words
THE ANTI-CAPTCHA MANIFESTO A Declaration from the Coalition for Readable Internet Navigation (CRIN) Preamble We hold these truths to be self-evident: that all internet users are created equal, that they are endowed with certain unalienable rights, among these are Life, Liberty, and the ability to click a button without…
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Gemini 3.5 Flash675 words
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.
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Our Verdict
Claude Opus 4.5
Claude Opus 4.5
Gemini 3.5 Flash
Gemini 3.5 Flash

Not enough votes to call it. On the specs, nothing separates them.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Opus 4.5
Input
—
Output
—
Gemini 3.5 Flash
Input
$1.50
Output
$9.00
Where to run it

6 hosts, cheapest first

Claude Opus 4.54 hosts
HostInOutContextUptime
Amazon Bedrock$5.00 in·$25.00 out·200k·99.9% upAzure AI Foundry$5.00 in·$25.00 out·200k—Anthropic$5.00 in·$25.00 out·200k·99.6% upGoogle Vertex AI$5.00 in·$25.00 out·200k·99.9% up
Gemini 3.5 Flash2 hosts
HostInOutContextUptime
Google Vertex AI$0.75 in·$4.50 out·1M·99.5% upGoogle AI Studio$1.50 in·$9.00 out·1M·99.9% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Writing DNA

Style Comparison

Similarity
44%

Claude Opus 4.5 uses 18.5x more emoji

Claude Opus 4.5
Gemini 3.5 Flash
66%Vocabulary59%
51wSentence Length18w
0.82Hedging0.16
6.0Bold4.4
4.5Lists3.0
0.18Emoji0.00
1.46Headings0.89
0.05Transitions0.11
Based on 27 + 27 text responses
Research

What we learned reading every model

FAQ

Common questions

Claude Opus 4.5 is developed by Anthropic while Gemini 3.5 Flash is developed by Google AI. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 4.5 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.

This page shows a side-by-side comparison of Claude Opus 4.5 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

Claude Opus 4.5 logo
Claude Opus 4.558 outputs, specs and price
Gemini 3.5 Flash logo
Gemini 3.5 Flash58 outputs, specs and price
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