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  5. Claude Opus 5.5vsGemini 3.1 Flash Lite
Updated Sep 2026

Claude Opus 5.5vsGemini 3.1 Flash Lite

Gemini 3.1 Flash Lite is cheaper than Claude Opus 5.5 at $0.25/M vs $4/M input tokens.

Claude Opus 5.5 and Gemini 3.1 Flash Lite compared across 19 shared prompts
SpecClaude Opus 5.5Gemini 3.1 Flash Lite
Input price$4/M tokens$0.25/M tokens
Output price$20/M tokens$1.5/M tokens
Context window1.0M tokens1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2026May 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 19 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 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 3.1 Flash Lite356 words
Financial Model (FY2026–FY2030) Transaction Assumptions (Entry): EV: $1,440m ($120m * 12.0x) Fees: $28.8m (2% of EV) Total Uses: $1,468.8m Debt: $660m (5.5x EBITDA) Term Loan: $480m Mezz: $180m Equity: $808.8m ($1,468.8m - $660m) ($m) FY2026 FY2027 FY2028 FY2029 FY2030 Revenue 972.0 1,040.0 1,102.4 1,157.5 1,215.4…
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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 3.1 Flash Lite323 words
Here is a simple, comforting, and delicious recipe that relies entirely on pantry staples. Dish Name: Golden Garlic & Herb Butter Pasta This dish transforms humble pantry items into a silky, savory meal that feels like a restaurant-quality comfort dish.
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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 Opus 5.5936 words
The 3 Weakest Claims in the MindMeld AI Pitch "Decodes neural patterns into text with 94% accuracy. Works with any language, any device." (Slide 3) Why it's weak: It far exceeds the published state of the art. The best results for thought-to-text come from invasive implants.
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Gemini 3.1 Flash Lite521 words
This pitch deck shows a high-potential "moonshot" technology, but it suffers from significant credibility gaps typical of early-stage deep-tech startups. Here are the three weakest claims and how to fix them. The Claim: "Predict what you want to type before you think it."
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Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

Claude Opus 5.53,435 words
The Transistor in 1920: A Counterfactual Through 1980 First, a Reality Check on the Premise A transistor "invented" in 1920 would not have changed the world in 1920. The actual 1947 transistor rested on three foundations that did not exist yet: Quantum theory of solids.
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Gemini 3.1 Flash Lite768 words
If the transistor had been invented in 1920—likely by researchers at Bell Labs or a similar entity—the "Electronic Age" would have arrived twenty-seven years earlier. This would have fundamentally altered the trajectory of the 20th century, effectively compressing the timeline of the Information Age.
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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 3.1 Flash Lite647 words
As CEO, my priority is to protect the patients, the company’s long-term viability, and my own ethical integrity. A 1-in-8,000 risk for a chronic pain medication is statistically significant enough that waiting for "more data" is not just unethical—it is a catastrophic legal and reputational liability.
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Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

Claude Opus 5.5653 words
Your 1-Month Starter Plan for Better Health & Longevity The philosophy: Small, consistent changes beat dramatic overhauls. Each week builds on the last, so by Day 30 you'll have a foundation of habits instead of a burned-out resolution.
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Gemini 3.1 Flash Lite501 words
This 30-day plan focuses on three pillars of health: Nutrition (Nutrient Density), Movement (Consistency), and Recovery (Sleep/Stress). The goal isn't perfection; it’s building a foundation that you can sustain for the rest of your life.
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Our Verdict
Claude Opus 5.5
Claude Opus 5.5
Gemini 3.1 Flash Lite
Gemini 3.1 Flash LiteRunner-up

Not enough votes to call it. On the specs, Claude Opus 5.5 has the edge: bigger model tier, newer.

Gemini 3.1 Flash Lite costs 13x less per token.

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 3.1 Flash Lite
Input
$0.25
16× cheaper
Output
$1.50
13× cheaper

Gemini 3.1 Flash Lite is cheaper on both: 16× input, 13× 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 3.1 Flash Lite2 hosts
HostInOutContextUptime
Google Vertex AI$0.13 in·$0.75 out·1M·99.7% upGoogle AI Studio$0.25 in·$1.50 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 3.1 Flash Lite is developed by Google AI. Claude Opus 5.5 has a 1.0M token context window vs Gemini 3.1 Flash Lite'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 3.1 Flash Lite 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 3.1 Flash Lite costs $0.25/M input tokens. Gemini 3.1 Flash Lite 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.

This page shows a side-by-side comparison of Claude Opus 5.5 and Gemini 3.1 Flash Lite 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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