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  5. Claude Opus 5.5vsGemini 3.6 Flash
Updated Sep 2026

Claude Opus 5.5vsGemini 3.6 Flash

Gemini 3.6 Flash is cheaper than Claude Opus 5.5 at $1.5/M vs $4/M input tokens.

Claude Opus 5.5 and Gemini 3.6 Flash compared across 19 shared prompts
SpecClaude Opus 5.5Gemini 3.6 Flash
Input price$4/M tokens$1.5/M tokens
Output price$20/M tokens$7.5/M tokens
Context window1.0M tokens1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2026Jul 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 19 prompts both answered. Formatting stripped, words untouched.

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 Opus 5.52,253 words
"Hive & Tide" Langoustine, Beeswax, White Chocolate & Oscietra Caviar, Hay-Baked Celeriac, Fermented Green Strawberry, Sea Buckthorn I. The Concept Most coastal menus celebrate the meeting of sea and land. This dish is about a stranger, quieter meeting: the meadow and the seabed, the bee and the langoustine.
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Gemini 3.6 Flash1,149 words
Shadows of the Forest & Shore Veal Sweetbreads & Torch-Cured Otoro with Fermented Rhubarb, Roasted Coffee-Glace, Sunchoke Silk, and Spruce Needle Oil Conceptual Narrative This dish explores the uncanny harmony between two rich, highly prized delicacies from opposing domains: the terrestrial richness of milk-fed veal…
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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 Opus 5.52,280 words
Architecture Review: Real-Time Collaborative Editor The most serious problems cluster in three areas: the sync model (client-clock LWW), cross-server propagation (per-server WebSockets with DB polling), and the CDN/auth layer, which can leak data between users. Issues are grouped by area below.
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Gemini 3.6 Flash1,163 words
This architecture contains several critical single points of failure, severe race conditions, data-loss mechanisms, and major performance bottlenecks. Below is a detailed breakdown of these issues categorized by domain, along with proposed architectural fixes and trade-offs.
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Mini LBO Underwrite

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

Claude Opus 5.5900 words
HarborTech Services: 5-Year LBO Underwriting Conventions: $m. Interest is charged on beginning-of-year balances, which avoids circularity. Term Loan (TL) amortization is 1% of the original $480m, or $4.8m per year. Mezz PIK accrues to principal. All FCF after mandatory debt service sweeps to the TL.
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Gemini 3.6 Flash656 words
Here is the completed LBO underwriting analysis for HarborTech Services (HTS). 1. Transaction Overview & Sources / Uses Entry Enterprise Value (EV): $120.0M EBITDA × 12.0x = $1,440.0M Transaction Fees: 2.0% × $1,440.0M = $28.8M Total Uses: $1,440.0M + $28.8M = $1,468.8M Term Loan (4.0x): $480.0M (9.0% cash interest…
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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 Opus 5.51,853 words
The Next 48 Hours: CEO Action Plan The Core Decision We disclose. The question is how to do it well, not whether. Before the schedule, here are the three facts that drive every decision below. 1. The harm is concrete.
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Gemini 3.6 Flash1,347 words
As CEO, my fundamental leadership principle in a crisis of this magnitude is: You cannot manage a crisis until you accept the full cost of doing the right thing. A safety issue of 1 in 8,000 patients over 5 years across a 4-million-patient population represents approximately 500 potential cases of liver failure.
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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 5.5300 words
Midnight Silk Noodles Creamy, tangy peanut noodles with a gentle kick, ready faster than takeout. Serves: 2 Prep time: 5 minutes Cook time: 10 minutes Total time: 15 minutes The 7 Ingredients 8 oz (225 g) spaghetti (or any long noodle) ¼ cup creamy peanut butter 3 tablespoons soy sauce 1 tablespoon honey (or sugar) 1…
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Gemini 3.6 Flash301 words
Velvet Honey-Garlic Chili Pasta This dish turns basic pantry staples into a restaurant-worthy meal in just 15 minutes. Rich butter, sweet honey, savory soy sauce, and a kick of red pepper flakes coat cooked pasta for the ultimate quick comforting dish.
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Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

Claude Opus 5.54,420 words
Contractor-Side Review of the Software Consulting Agreement Overall assessment: This agreement is heavily one-sided. Nearly every clause shifts risk, cost, or control to the Contractor, and several provisions interact to create compounding exposure.
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Gemini 3.6 Flash1,124 words
This draft agreement is extremely one-sided and predatory. Almost every clause contains severe risks that could allow the Client to extract free labor, seize your pre-existing intellectual property, bankrupt you through uncapped liabilities, or prevent you from working in your field.
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Our Verdict
Claude Opus 5.5
Claude Opus 5.5
Gemini 3.6 Flash
Gemini 3.6 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 5.5
Input
$4.00
Output
$20.00
Gemini 3.6 Flash
Input
$1.50
2.7× cheaper
Output
$7.50
2.7× cheaper

Gemini 3.6 Flash is cheaper on both: 2.7× input, 2.7× output.

Where to run it

6 hosts, cheapest first

Claude Opus 5.54 hosts
HostInOutContextUptime
Amazon Bedrock$4.00 in·$20.00 out·1M·99.8% upAzure AI Foundry$4.00 in·$20.00 out·1M·100% upAnthropic$4.00 in·$20.00 out·1M·100% upGoogle Vertex AI$4.00 in·$20.00 out·1M·100% up
Gemini 3.6 Flash2 hosts
HostInOutContextUptime
Google Vertex AI$0.38 in·$1.88 out·1M·99.2% upGoogle AI Studio$0.75 in·$3.75 out·1M·99.9% up

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

Research

What we learned reading every model

FAQ

Common questions

Claude Opus 5.5 is developed by Anthropic while Gemini 3.6 Flash is developed by Google AI. Claude Opus 5.5 has a 1.0M token context window vs Gemini 3.6 Flash's 1.0M. You can compare their actual outputs across 19 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 5.5 and Gemini 3.6 Flash each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 19 challenges so you can judge which fits your needs best.

Claude Opus 5.5 costs $4/M input tokens and Gemini 3.6 Flash costs $1.5/M input tokens. Gemini 3.6 Flash is $2.50/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 Opus 5.5 and Gemini 3.6 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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