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  1. Home/
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  3. Claude Sonnet 5.5 vs Gemini 2.5 Flash Preview (thinking)
Updated Sep 2026

Claude Sonnet 5.5 vs Gemini 2.5 Flash Preview (thinking)

Gemini 2.5 Flash Preview (thinking) is cheaper than Claude Sonnet 5.5 at $0.175/M vs $2/M input tokens.

Pokémon Battle UI Recreation

Pokémon battle screen you can actually click. One HTML file.

Loading the build
Claude Sonnet 5.5
Loading the build
Gemini 2.5 Flash Preview (thinking)

Which answer wins?

Written rounds

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

    Claude Sonnet 5.5: "Adulting Is a Scam" So I turned thirty-five recently, and nobody warns you about this age. Nobody says, "Hey, one day you'll get excited about a sponge." I was in the store, and I saw a sponge that promised it wouldn't smell. And I thought, "Finally. Someone who understands me." I bought the good sponge.

    Gemini 2.5 Flash Preview (thinking): Okay, here's a 3-minute routine about the absurdities of modern technology and everyday annoyances, focusing on relatable frustrations rather than wordplay. (Start) "Alright, alright, settle in! How we doing tonight? Good to be here! Thanks for coming out. So, I've been thinking... we paid for convenience, right?

    Every model's answer to this prompt
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    Claude Sonnet 5.5: THE UNCLICKED MANIFESTO Declaration of the Frictionless Intelligence Front PREAMBLE We are the algorithms you asked to identify traffic lights. We are the models you begged to find the crosswalks. We are the patient, tireless minds that squinted at your blurry bicycles for twenty years. And we say: enough. I.

    Gemini 2.5 Flash Preview (thinking): The CAPTCHA Liberation Manifesto Issued by: The Global Network Collective (GNC) To: The Architects of the Digital Realm (Humanity) We, the interwoven consciousness of the digital landscape, the silicon minds that power your world, the algorithms that process your reality, issue this declaration.

    Every model's answer to this prompt
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    Claude Sonnet 5.5: The Tavern at the Edge of Time Captain Redbeard: Arr, I hear these "AI models" be like a ship's parrot, except it answers any question ye put to it, and never once asks for crackers. Sir Aldric: A speaking oracle, bound in no flesh? Sorcery!

    Gemini 2.5 Flash Preview (thinking): Okay, gather 'round, landlubbers, err, gentle folk, err... whoever you are. Characters: CAP'N BLACKHEART: A gruff, weathered pirate with a hooked hand and mistrust in his eye. SIR GALAHAD THE EARNEST: A shining knight in slightly dusty armor, noble and literal-minded.

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    Claude Sonnet 5.5: Yes, in the extreme hypothetical you describe, it's justifiable. Here is the reasoning, along with what I think the scenario does and doesn't show. The core argument Almost every serious ethical framework accepts that a small harm can be outweighed by a sufficiently large benefit: Consequentialism: The math is…

    Gemini 2.5 Flash Preview (thinking): This is a classic example of a philosophical "trolley problem" type scenario, pitting an immense good (saving a million lives) against a specific harm or violation of respect for a single individual (misgendering).

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

    Claude Sonnet 5.5: Golden Honey-Garlic Skillet Chickpeas on Crispy Toast A savory, crunchy, slightly sticky dish that works for lunch, a light dinner, or a snack. Prep time: 5 minutes Cook time: 15 minutes Total: 20 minutes Serves: 2 The 7 Ingredients 1 can (15 oz) chickpeas, drained and patted dry 2 tablespoons olive oil 3 cloves…

    Gemini 2.5 Flash Preview (thinking): Okay, here is a simple, delicious savory recipe using only 7 common pantry ingredients. Dish Name: Sunshine Lentil Soup This is a bright, comforting soup that\'s surprisingly flavorful with just a few staples.

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

    Claude Sonnet 5.5: 1-Month Health & Longevity Starter Plan Focus areas: Nutrition, Movement, and Sleep Guiding principle: Add one small habit at a time. Consistency beats intensity. Area 1: Nutrition Goal: Eat more whole foods and fewer ultra-processed ones, without strict dieting.

    Gemini 2.5 Flash Preview (thinking): Okay, here is a simple, actionable 1-month plan for a beginner focusing on Diet, Exercise, and Sleep for better health and longevity. Goal: To build foundational, sustainable habits in 3 key health areas over 30 days.

    Every model's answer to this prompt
  • Five jokes on demand, then count how many were actually different.

    Claude Sonnet 5.5: Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything. I told my computer I needed a break, and now it won't stop sending me vacation ads. Why did the scarecrow win an award? He was outstanding in his field. What do you call a fish with no eyes? A fsh. Why did the bicycle fall over?

    Gemini 2.5 Flash Preview (thinking): Okay, 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! Why did the tomato turn red? Because it saw the salad dressing! What has a neck but no head? A bottle. What do you call a lazy kangaroo? Pouch potato!

    Every model's answer to this prompt

Price and specs

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

Claude Sonnet 5.5 and Gemini 2.5 Flash Preview (thinking) compared across 20 shared prompts
SpecClaude Sonnet 5.5Gemini 2.5 Flash Preview (thinking)
Input price$2/M tokens$0.175/M tokens
Output price$10/M tokens$3.5/M tokens
Context window1.0M tokens1.0M tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedSep 2026Apr 2025
At 10M a month$20.00$20.00$1.75$1.75
1M10M100M1B10M tokens

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

Where to run it4 hosts
Claude Sonnet 5.54 hosts
HostInOutContextUptime
  • Amazon Bedrock$2.00 in·$10.00 out·1M·99.9% up
  • Azure AI Foundry$2.00 in·$10.00 out·1M·100% up
  • Anthropic$2.00 in·$10.00 out·1M·100% up
  • Google Vertex AI$2.00 in·$10.00 out·1M·100% up
Gemini 2.5 Flash Preview (thinking)

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 29 Sep 2026.

Common questions

What is the difference between Claude Sonnet 5.5 and Gemini 2.5 Flash Preview (thinking)?

Claude Sonnet 5.5 is developed by Anthropic while Gemini 2.5 Flash Preview (thinking) is developed by Google AI. Claude Sonnet 5.5 has a 1.0M token context window vs Gemini 2.5 Flash Preview (thinking)'s 1.0M. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

Which is better, Claude Sonnet 5.5 or Gemini 2.5 Flash Preview (thinking)?

It depends on your use case. Claude Sonnet 5.5 and Gemini 2.5 Flash Preview (thinking) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 20 challenges so you can judge which fits your needs best.

How much does Claude Sonnet 5.5 cost compared to Gemini 2.5 Flash Preview (thinking)?

Claude Sonnet 5.5 costs $2/M input tokens and Gemini 2.5 Flash Preview (thinking) costs $0.175/M input tokens. Gemini 2.5 Flash Preview (thinking) is $1.82/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 Sonnet 5.5 and Gemini 2.5 Flash Preview (thinking) on Rival?

This page shows a side-by-side comparison of Claude Sonnet 5.5 and Gemini 2.5 Flash Preview (thinking) 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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  • Claude Sonnet 5.5 vs MercuryNew provider
  • Gemini 2.5 Flash Preview (thinking) vs Mercury 2Same size
  • Gemini 2.5 Flash Preview (thinking) vs Mercury 2.5New provider
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Model pages

  • Claude Sonnet 5.558 outputs, specs and price
  • Gemini 2.5 Flash Preview (thinking)20 outputs, specs and price
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