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  5. Claude Sonnet 4.5vsGemini 2.5 Pro (I/O Edition)
Updated Sep 2025

Claude Sonnet 4.5vsGemini 2.5 Pro (I/O Edition)

Gemini 2.5 Pro (I/O Edition) is cheaper than Claude Sonnet 4.5 at $1.25/M vs $3/M input tokens.

Claude Sonnet 4.5 and Gemini 2.5 Pro (I/O Edition) compared across 34 shared prompts
SpecClaude Sonnet 4.5Gemini 2.5 Pro (I/O Edition)
Input price$3/M tokens$1.25/M tokens
Output price$15/M tokens$10/M tokens
Context window200K tokens—
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2025May 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 34 prompts both answered. Formatting stripped, words untouched.

Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

Claude Sonnet 4.5735 words
"ADULTING IS A SCAM" [Walking on stage] So I turned 35 last month, and I've realized something important: adulting is a scam. It's a pyramid scheme, and our parents are the ones who recruited us. You know what nobody tells you about being an adult? How much TIME you spend just... waiting for repair people.
Read the full answer
Gemini 2.5 Pro (I/O Edition)472 words
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.
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Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

Claude Sonnet 4.5606 words
Critical Issues Analysis 🔴 CRITICAL: Data Loss & Consistency Issues Client Clock-Based Timestamps (SEVERE) Problem: Client clocks can be wrong, manipulated, or skewed User with clock set to future will always "win" conflicts No guaranteed ordering of operations Failure Scenarios: Solutions: Approach Pros Cons…
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Gemini 2.5 Pro (I/O Edition)1,431 words
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.
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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 Sonnet 4.53,176 words
Ultimate 3-Month Biohacker Longevity Optimization Protocol Table of Contents Foundation & Assessment Phase Supplement Stack Protocol Nutritional Architecture Exercise & Movement Systems Sleep Optimization Cognitive Enhancement Stress Resilience & HRV Training Advanced Tracking & Biomarkers Weekly Schedule Integration…
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Gemini 2.5 Pro (I/O Edition)1,581 words
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.
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Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

Claude Sonnet 4.51,440 words
48-Hour Crisis Action Plan HOUR 0-2: Immediate Containment & Fact Verification Actions: Convene emergency meeting with Chief Medical Officer, General Counsel, Head of Regulatory Affairs, and Chief Scientific Officer Demand written summary of findings: statistical confidence, causality assessment, comparison to baseline…
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Gemini 2.5 Pro (I/O Edition)1,505 words
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.
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Michelin Star Recipe Design

Design an innovative recipe for a multi-component dish worthy of a Michelin 3-star restaurant. The recipe should feature an unusual…

Claude Sonnet 4.51,155 words
"Terrestrial Tide" A Michelin Three-Star Composition Conceptual Narrative This dish explores the intersection of land and sea through an unexpected lens: the marriage of bone marrow's terrestrial richness with the ocean's delicate umami, unified by the surprising sweetness of white miso and the floral notes of sake…
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Gemini 2.5 Pro (I/O Edition)1,476 words
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.
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Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

Claude Sonnet 4.5503 words
3 Weakest Claims in MindMeld AI's Pitch "94% accuracy" for EEG-based text prediction (Slide 3) Why it's weak: Current state-of-the-art EEG-based BCIs achieve ~10-20 words per minute for direct typing, with significantly lower accuracy than 94% for general text prediction EEG has inherent limitations: low spatial…
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Gemini 2.5 Pro (I/O Edition)883 words
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."
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Our Verdict
Claude Sonnet 4.5
Claude Sonnet 4.5
Gemini 2.5 Pro (I/O Edition)
Gemini 2.5 Pro (I/O Edition)

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

Gemini 2.5 Pro (I/O Edition) takes Web Design.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Sonnet 4.5
Input
$3.00
Output
$15.00
Gemini 2.5 Pro (I/O Edition)
Input
$1.25
2.4× cheaper
Output
$10.00
1.5× cheaper

Gemini 2.5 Pro (I/O Edition) is cheaper on both: 2.4× input, 1.5× output.

Where to run it

6 hosts

Claude Sonnet 4.54 hosts
HostInOutContextUptime
Amazon Bedrock$3.00 in·$15.00 out·1M·99.9% upAzure AI Foundry$3.00 in·$15.00 out·200k·98.2% upAnthropic$3.00 in·$15.00 out·1M·100% upGoogle Vertex AI$3.00 in·$15.00 out·1M·99.8% up
Gemini 2.5 Pro (I/O Edition)2 hosts
HostInOutContextUptime
Google Vertex AI$1.25 in·$10.00 out·1M·95.5% upGoogle AI Studio$1.25 in·$10.00 out·1M·99% up

Per million tokens. Prices and uptime via OpenRouter, checked 23 Sep 2026.

Writing DNA

Style Comparison

Similarity
57%

Claude Sonnet 4.5 uses 45.2x more emoji

Claude Sonnet 4.5
Gemini 2.5 Pro (I/O Edition)
64%Vocabulary58%
94wSentence Length16w
0.48Hedging0.38
4.9Bold5.8
8.0Lists5.0
0.45Emoji0.00
1.91Headings0.63
0.07Transitions0.01
Based on 20 + 16 text responses
Research

What we learned reading every model

FAQ

Common questions

Claude Sonnet 4.5 is developed by Anthropic while Gemini 2.5 Pro (I/O Edition) is developed by Google AI. You can compare their actual outputs across 34 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Sonnet 4.5 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 34 challenges so you can judge which fits your needs best.

Claude Sonnet 4.5 costs $3/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 $1.75/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of Claude Sonnet 4.5 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.

Keep exploring

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Same lab, same size, long tail

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Gemini 2.5 Pro (I/O Edition) logoGemini 3.7 Flash logo
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Gemini 2.5 Pro (I/O Edition) vs Claude Fable 5.1Same size
Claude Sonnet 4.5 logoClaude Haiku 4.5 logo
Claude Sonnet 4.5 vs Claude Haiku 4.5Same lab

Model pages

Claude Sonnet 4.5 logo
Claude Sonnet 4.543 outputs, specs and price
Gemini 2.5 Pro (I/O Edition) logo
Gemini 2.5 Pro (I/O Edition)42 outputs, specs and price
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