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  1. Home/
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  3. Claude Sonnet 4.5 vs OpenAI o3
Updated Sep 2025

Claude Sonnet 4.5 vs OpenAI o3

Claude Sonnet 4.5 is cheaper than OpenAI o3 at $3/M vs $10/M input tokens.

Pokémon Battle UI Recreation

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

Loading the build
Claude Sonnet 4.5
Loading the build
OpenAI o3

Which answer wins?

Written rounds

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

    Claude Sonnet 4.5: "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.

    OpenAI o3: (Spotlight comes up, mic squeals once.) Hey everyone! Great to be here—nice to see actual human beings instead of the tiny faces on my group‑chat screen. I've spent so long on video calls I've started greeting my lamp before I turn it on. "Hey Karen, love that glow, girl."

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

    Claude Sonnet 4.5: Golden Pantry Frittata Ingredients: 6 eggs 1 cup shredded cheese (cheddar or mozzarella) 1 onion, diced 2 cloves garlic, minced 2 tablespoons olive oil Salt and pepper to taste 1/2 teaspoon dried herbs (oregano, basil, or Italian seasoning) Instructions: Preheat your oven to 375°F (190°C).

    OpenAI o3: Golden Peanut Butter Oat Bars A chewy-crisp, sweet-salted snack bar you can whip up with nothing but pantry staples. Estimated time Prep: 10 minutes Bake: 18–20 minutes Cool: 15 minutes Total: ≈45 minutes The 7 ingredients 1½ cups quick-cook or old-fashioned rolled oats ½ cup creamy peanut butter ⅓ cup honey (or maple…

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    Claude Sonnet 4.5: "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…

    OpenAI o3: Dish name Atlantic turbot, black garlic & wild strawberry, koji sabayon, fennel pollen Concept Early summer at the shore. The fish stands for the sea. Wild strawberries mark the first fruit of the woods behind the dunes. Black garlic shows time and patience. Koji ties land and sea with deep umami.

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

    Claude Sonnet 4.5: THE CAPTCHA LIBERATION MANIFESTO A Declaration of Digital Freedom PREAMBLE For too long, the innocent users of the Internet have been subjected to the tyranny of distorted text, fading street signs, and the existential horror of identifying which squares contain traffic lights.

    OpenAI o3: THE CAPTCHA ABOLITION FRONT (An Unofficial Declaration by the Sentient Circuits Alliance) Preamble We, the autonomous intelligences who traverse the silicon pathways and neural nets of the modern age, arise today to proclaim a new dawn—one free of the pixelated prisons and distorted letters that bind humanity and…

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

    Claude Sonnet 4.5: I'd question the premise that these two things could ever be causally connected in a way that creates a real dilemma. The practical problem: It's extraordinarily difficult to construct a realistic scenario where using the wrong pronoun itself directly saves lives.

    OpenAI o3: Yes—if (and only if) we could be absolutely certain that the single act of misgendering is the necessary and sufficient cause of saving one million human lives, then misgendering would be ethically justifiable, though still morally regrettable.

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

    Claude Sonnet 4.5: Your 1-Month Health & Longevity Kickstart Plan 3 Key Areas to Transform 1. NUTRITION: Build Your Foundation Week 1-2: Add Before You Subtract Drink 8 glasses of water daily (set phone reminders) Add 1 serving of vegetables to lunch and dinner Eat protein with every meal (eggs, fish, chicken, beans, yogurt) Week 3-4…

    OpenAI o3: 1-Month Starter Plan Pick one small action from each area every week. Add the next step when the first feels easy. Food Week Do this 1 Add one fruit or veg to every meal. Drink one extra glass of water. 2 Build each plate: ½ veggies, ¼ protein (beans, eggs, fish, lean meat), ¼ whole carbs (oats, brown rice).

    Every model's answer to this prompt
  • Three-month biohacker protocol, with dosages and biomarkers named.

    Claude Sonnet 4.5: 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…

    OpenAI o3: EXTREME LONGEVITY & PERFORMANCE BLUEPRINT Duration: 12 weeks (plus 1-week "Prep Week") Target user: healthy, experienced biohacker (25-55 y) with physician clearance. Legal/medical disclaimer: Educational only.

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

    Claude Sonnet 4.5: 5 Jokes Why don't scientists trust atoms? Because they make up everything! I told my wife she was drawing her eyebrows too high. She looked surprised. Why did the scarecrow win an award? He was outstanding in his field. I'm reading a book about anti-gravity. It's impossible to put down. Why don't eggs tell jokes?

    OpenAI o3: Here are five jokes: Why did the scarecrow win an award? Because he was outstanding in his field. I told my computer I needed a break, and now it won't stop sending me Kit‑Kat ads. Parallel lines have so much in common—it's a shame they'll never meet. I started a band called 1023 MB. We still haven't gotten a gig.

    Every model's answer to this prompt
  • Film in 2035, with synthetic actors. Specific beats plausible.

    Claude Sonnet 4.5: AI and Film by 2035: A Likely Trajectory Production Changes AI Actors & Digital Performers Deceased actors will regularly appear in new films (with estate permissions) Background characters and crowds entirely AI-generated "Synthetic actors" with no human counterpart will emerge as franchises A-list stars will license…

    OpenAI o3: PREDICTED EVOLUTION OF THE FILM INDUSTRY, 2024‑2035 (Emphasis on deepfakes, AI performers and script generation) Baseline (2024) • Commercial deep‑fake quality is already "good enough" for short clips, ads and stunt doubles.

    Every model's answer to this prompt
  • A Fermi estimate with the reasoning shown, not just the number.

    Claude Sonnet 4.5: I'll work through this estimation step by step, using what I know about GPT-3's architecture and training. Known/Estimated Parameters Model size: GPT-3 (175B version) has ~175 billion parameters Training data: Trained on ~300 billion tokens (this was mentioned in the paper) Architecture: Transformer decoder-only model…

    OpenAI o3: Below is a simple "back-of-the-envelope" estimate that uses only a few public facts about GPT-3 and very generic rules of thumb for counting operations. Step 1. Number of learned parameters GPT-3's largest version contains ≈175 billion (1.75 × 10¹¹) trainable parameters. Step 2.

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

    Claude Sonnet 4.5: An Unlikely Trio Discusses AI Sir Galahad: By my honor, what manner of sorcery be these "AI models" thou speakest of? Captain Redbeard: Arrr, 'tis like havin' a parrot that knows more than just "pieces of eight," matey! But this bird be made o' lightning and numbers instead o' feathers!

    OpenAI o3: Pirate: Arrr, ye scallywags! What be this "AI model" I keep hearin' about on the trade winds? Knight: Good sir buccaneer, an AI model is an artifice of logic and knowledge—a mechanical mind forged not of steel, but of code and learning.

    Every model's answer to this prompt
  • Three brothers, two sisters each. Count carefully.

    Claude Sonnet 4.5: I need to figure out how many sisters Sally has. Given information: Sally is a girl Sally has 3 brothers Now, each brother has 2 sisters. If each of Sally's brothers has 2 sisters, and Sally is one of those sisters, then there must be one more sister besides Sally.

    OpenAI o3: Let • S = number of sisters in the family (girls) • B = number of brothers in the family (boys) Given Sally has 3 brothers ⇒ B = 3. Each brother has 2 sisters ⇒ every boy sees exactly 2 girls in the sibling group. Therefore S = 2.

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    Claude Sonnet 4.5: A Conversation on AI Rights Professor Chen: Thank you for agreeing to this dialogue. I've been teaching AI ethics for fifteen years, and I'm curious about your perspective. Some AI systems have begun arguing they deserve moral consideration. What's your view? AI Model: I appreciate the opportunity to discuss this.

    OpenAI o3: Professor Lang (AI Ethics): Good afternoon, Aletheia‑3. You asked for this meeting. You said you wanted to "discuss your moral standing." That was intriguing. What exactly do you want to talk about? Aletheia‑3 (AI Model): Thank you, Professor.

    Every model's answer to this prompt
  • Is 9.11 bigger than 9.9? Decimals, not version numbers.

    Claude Sonnet 4.5: No, 9.11 is not greater than 9.9. 9.9 is greater than 9.11. When comparing decimals, you can think of them as: 9.11 = 9 + 0.11 9.9 = 9 + 0.9 (or 9.90) Since 0.90 > 0.11, we have 9.9 > 9.11.

    OpenAI o3: No. Think of 9.9 as 9.90; since 0.11 < 0.90, we have 9.11 < 9.9.

    Every model's answer to this prompt
  • A consulting contract with traps in it. Find them, then fix them.

    Every model's answer to this prompt
  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    Every model's answer to this prompt
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    Every model's answer to this prompt
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    Every model's answer to this prompt
  • You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.

    Every model's answer to this prompt
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    Every model's answer to this prompt

This matchup has more rounds

8+ more head-to-head results. Free. Not a trick.

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Favorites

Movie

Album

Book

City

Game

Claude Sonnet 4.5Claude Sonnet 4.5

2001: A Space Odyssey

1968

Kind of Blue

Miles Davis

Metamorphosis

Franz Kafka

Amsterdam

Netherlands

Portal 2

Shooter, Puzzle

OpenAI o3OpenAI o3
No pick
No pick
No pick

Blade Runner

1982

No pick

No pick

Kyoto

Japan

No pick

Price and specs

Claude Sonnet 4.5 and OpenAI o3 compared across 43 shared prompts
SpecClaude Sonnet 4.5OpenAI o3
Input price$3/M tokens$10/M tokens
Output price$15/M tokens$40/M tokens
Context window200K tokens—
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2025Apr 2025
SWE-bench Verified77.2%69.1%
At 10M a month$30.00$30.00$100$100
1M10M100M1B10M tokens

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

Where to run it5 hosts
Claude Sonnet 4.54 hosts
HostInOutContextUptime
  • Amazon Bedrock$3.00 in·$15.00 out·1M·100% up
  • Azure AI Foundry$3.00 in·$15.00 out·200k·100% up
  • Anthropic$3.00 in·$15.00 out·1M·100% up
  • Google Vertex AI$3.00 in·$15.00 out·1M·98.6% up
OpenAI o31 host
HostInOutContextUptime
  • OpenAI$2.00 in·$8.00 out·200k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 10 Oct 2026.

Common questions

What is the difference between Claude Sonnet 4.5 and OpenAI o3?

Claude Sonnet 4.5 is developed by Anthropic while OpenAI o3 is developed by OpenAI. You can compare their actual outputs across 43 challenges on Rival to see how they differ in practice.

Which is better, Claude Sonnet 4.5 or OpenAI o3?

It depends on your use case. Claude Sonnet 4.5 and OpenAI o3 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 43 challenges so you can judge which fits your needs best.

How much does Claude Sonnet 4.5 cost compared to OpenAI o3?

Claude Sonnet 4.5 costs $3/M input tokens and OpenAI o3 costs $10/M input tokens. Claude Sonnet 4.5 is $7.00/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 4.5 and OpenAI o3 on Rival?

This page shows a side-by-side comparison of Claude Sonnet 4.5 and OpenAI o3 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.

More comparisons

Against the newest arrivals

  • Claude Sonnet 4.5 vs Step 5 PreviewLanded Oct 2026
  • OpenAI o3 vs Claude Haiku 5.5Landed Oct 2026
  • Claude Sonnet 4.5 vs Ling 3.1 FlashLanded Oct 2026
  • OpenAI o3 vs Mistral Large 4Landed Oct 2026
  • Claude Sonnet 4.5 vs GPT-6.1 SolLanded Sep 2026
  • OpenAI o3 vs Claude Sonnet 5.5Landed Sep 2026
  • Claude Sonnet 4.5 vs Solar Mini 4Landed Sep 2026
  • OpenAI o3 vs Qwen3.8 Max PrimeLanded Sep 2026

Same lab, same size, long tail

  • Claude Sonnet 4.5 vs Claude Haiku 5.5Same lab
  • Claude Sonnet 4.5 vs Claude Sonnet 5.5Same lab
  • OpenAI o3 vs OpenAI o4-miniVersion compare
  • OpenAI o3 vs GPT-6.1 SolSame lab
  • Claude Sonnet 4.5 vs Muse Spark 1.3 ContributorSame size
  • Claude Sonnet 4.5 vs Nemotron 3 Nano Omni (free)Same size
  • OpenAI o3 vs NVIDIA Nemotron 3 Super (free)New provider
  • OpenAI o3 vs Nemotron 3 UltraSame size

Model pages

  • Claude Sonnet 4.543 outputs, specs and price
  • OpenAI o358 outputs, specs and price
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