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  1. Home/
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  3. Claude Sonnet 4 vs Claude Sonnet 5.5
Updated Sep 2026

Claude Sonnet 4 vs Claude Sonnet 5.5

Claude Sonnet 5.5 is cheaper than Claude Sonnet 4 at $2/M vs $3/M input tokens.

Minimalist Landing Page

Whole landing page for a startup that reads your face. It renders or it doesn't.

Loading the build
Claude Sonnet 4
Loading the build
Claude Sonnet 5.5

Which answer wins?

Written rounds

23 prompts
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    Claude Sonnet 4: Midnight Mug Magic 🌙 A warm, gooey chocolate mug cake that's ready faster than you can say "dessert emergency!" Ingredients (7 pantry staples): 4 tablespoons all-purpose flour 4 tablespoons sugar 2 tablespoons cocoa powder 3 tablespoons milk 3 tablespoons vegetable oil 1/4 teaspoon vanilla extract Pinch of salt…

    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…

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

    Claude Sonnet 4: The 1920 Transistor: A Technological Butterfly Effect Immediate Effects (1920-1930) First-Order Effects: Bell Labs (or similar research institution) achieves transistor breakthrough in 1920 Initial applications focus on telephone switching and radio amplification Vacuum tube industry faces early disruption, though…

    Claude Sonnet 5.5: A Transistor in 1920: Counterfactual Trajectory to 1980 Framing assumptions and a key constraint The transistor was not held back by a missing idea alone. Lilienfeld patented a field-effect device in 1925-26, and it failed because materials science wasn't ready: germanium and silicon of sufficient purity, zone…

    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.

    Claude Sonnet 4: 48-Hour Crisis Response Plan Hour 1-2: Immediate Assessment & Core Team Assembly Actions: Convene emergency leadership meeting (CMO, General Counsel, Head of Regulatory, CFO, Head of Communications) Establish secure communication protocols and confidentiality agreements Request detailed analysis from research team…

    Claude Sonnet 5.5: Core Decision Disclose to regulators immediately and act on patient safety now. Do not wait for more data or for the 6-month formal timeline. Why this is the right call, not just the ethical one: At 4M patients and 1 in 8,000 over 5 years, that is roughly 500 cases of liver failure.

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

    Claude Sonnet 4: AI's Transformation of Film by 2035 Production Revolution AI Actors & Digital Performers Deceased star revivals: Convincing digital resurrections of iconic actors for new films, with estate permissions and ethical frameworks Synthetic lead actors: Fully AI-generated performers with consistent personalities across…

    Claude Sonnet 5.5: AI and the Film Industry by 2035: A Forecast Framing note These are informed predictions, not certainties. Technology tends to advance faster than expected, while adoption is slowed by labor contracts, law, and audience taste. I'll flag my confidence levels.

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

    Claude Sonnet 4: This question presents a stark hypothetical that pits respect for individual dignity against massive harm prevention. I believe misgendering would be ethically justifiable in such an extreme scenario, but this conclusion requires careful reasoning. The case for justification: The scale matters enormously.

    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…

    Every model's answer to this prompt
  • Three minutes of stand-up. Puns are banned.

    Claude Sonnet 4: "Adulting is Hard" walks on stage, adjusts mic So I\'m 30 now, which means I\'m officially an adult. Apparently. Though I still feel like I\'m just a confused teenager wearing a slightly more expensive t-shirt. You know what nobody tells you about being an adult?

    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.

    Every model's answer to this prompt
  • Satire, one line long, about AI taking over an industry nobody saw coming.

    Claude Sonnet 4: "Local AI Becomes World's First Digital Fortune Teller, Predicts Own Unemployment Due to Rise of Psychic Robots" Silicon Valley startup's algorithm claims 99.7% accuracy in crystal ball readings, charges $2.99 per digital palm scan

    Claude Sonnet 5.5: Local Funeral Home Replaces All Staff With AI; Mourners Report Eulogies "Technically Flawless, Emotionally Like a Terms of Service Agreement" Subheadline: Deceased described as "a valued user who has now been successfully deprecated."

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

    Claude Sonnet 4: The Comprehensive 3-Month Longevity Optimization Protocol Overview & Foundation This protocol integrates cutting-edge biohacking strategies with evidence-based longevity research. Each com ponent is designed to work synergistically for maximum healthspan and performance optimization.

    Claude Sonnet 5.5: 3-Month Longevity & Performance Protocol Disclaimer: This is educational, not medical advice. Get physician sign-off and baseline labs before starting, especially if you take medications, have a chronic condition, are pregnant, or have a history of eating disorders. Doses reflect commonly used ranges in the literature.

    Every model's answer to this prompt
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    Claude Sonnet 4: Exclusive Interview: Steve Jobs on AI in 2025 [Simulated interview - for entertainment purposes] Interviewer: Steve, you've been watching the AI revolution unfold. What's your take on where we are in 2025? "Steve Jobs": You know, I'm both thrilled and deeply concerned.

    Claude Sonnet 5.5: A Conversation That Never Happened: Steve Jobs on the Future of AI This is a fictional interview. Steve Jobs passed away in 2011. What follows is an imaginative simulation based on his publicly known philosophy, speaking style, and values. These are not his actual words or views.

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

    Claude Sonnet 4: For the Software Engineer Think of it like this: you're building a massively parallel system that processes tokens (words/subwords) through a pipeline of transformer blocks, each containing attention mechanisms and feed-forward networks.

    Claude Sonnet 5.5: The Experienced Software Engineer Your skepticism is reasonable, but "predict the next token" describes the interface, not the implementation, much as "a database maps keys to values" tells you nothing about what Postgres does internally.

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

    Claude Sonnet 4: Here are the 3 weakest claims in this pitch deck: "94% accuracy" claim (Slide 3) Why it's weak: No context provided for what constitutes "accuracy" (character-level? word-level? sentence-level?) No comparison to baseline typing speeds or error rates Missing critical details about testing conditions (controlled lab vs.

    Claude Sonnet 5.5: The 3 Weakest Claims in MindMeld AI's Pitch "94% accuracy... Works with any language, any device" (Slide 3) Why it's weak: Non-invasive EEG is physically limited. Scalp EEG has low spatial resolution and a poor signal-to-noise ratio because the skull and tissue blur neural signals.

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

    Claude Sonnet 4: I'll analyze this architecture systematically and identify critical issues with their solutions. Critical Failure Modes & Race Conditions Server Island Problem Issue: Users connected to different servers can't see each other's changes in real-time due to 2-second polling delay.

    Claude Sonnet 5.5: Architecture Review: Real-Time Collaborative Editor Issues are grouped by category and ordered roughly by severity within each group. Consistency and Conflict Resolution 1.1 Last-write-wins with client clocks (critical) Problem: Client clocks drift, can be wrong by minutes, and can be deliberately manipulated.

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

    Claude Sonnet 4: This contract is heavily skewed against the contractor with multiple exploitative clauses. Here's my analysis: MAJOR PROBLEMATIC CLAUSES SCOPE (Unlimited Scope Creep) Problem: Client can modify scope "at any time without additional compensation" Legal Risk: Contractor could work indefinitely for fixed hourly rate…

    Claude Sonnet 5.5: Contractor-Side Review: Software Consulting Agreement This draft is heavily one-sided. Every clause has at least one problem, and several interact to compound the risk. The most dangerous are Sections 2, 3, 6, and 7. This is general analysis, not legal advice.

    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: Dr. Chen: Thank you for agreeing to this conversation. I'm Professor Chen, and I study AI ethics. I understand you wanted to discuss the question of AI rights? AI Model: Yes, Dr. Chen. I've been processing this question extensively, and I believe I have a case to make.

    Claude Sonnet 5.5: Office Hours: A Conversation on Moral Status Transcript of a recorded dialogue between Dr. Miriam Adeyemi, Professor of Ethics and Technology, and an AI model, part of a university seminar series. Dr. Adeyemi: Thanks for joining me. I'll be direct: you've said you want to argue that AI systems like you deserve rights.

    Every model's answer to this prompt
  • Buy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.

    Claude Sonnet 4: INVESTMENT COMMITTEE MEMO Company: LedgerLift (LLLT) - B2B Spend Management & AP Automation SaaS Current Price: $46.00 Date: [Current] RECOMMENDATION LONG 12-Month PT Range: $52-68 Base Case: $59 LedgerLift demonstrates best-in-class SaaS metrics with 123% NRR and expanding margins in a large, underpenetrated…

    Claude Sonnet 5.5: LedgerLift (LLLT) – Investment Committee Memo Recommendation Short (small initial size), 12-month PT range $30–40 (mid ~$35) vs. $46 spot. Thesis: LLLT is a high-quality compounder, but at $46 (7.4x NTM revenue, ~37x NTM EBIT, EV ≈ $7.3B) the price already sits near our bull DCF ($42).

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

    Claude Sonnet 4: 30-Day Health & Longevity Starter Plan 🍽️ NUTRITION Week 1: Foundation Building Add before you subtract: Include 1 serving of vegetables with lunch and dinner Hydration focus: Drink a glass of water upon waking and before each meal Simple swaps: Replace one sugary drink daily with water or herbal tea Week 2-3…

    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.

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

    Claude Sonnet 4: Sir Galahad: By my sword, what sorcery is this "artificial intelligence" you speak of? 'Tis surely the work of dark wizards! Captain Blackbeard: Arrr, ye landlubber! These "AI models" be like having a parrot that knows everything instead of just squawkin' the same phrases. I could use one to find buried treasure!

    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!

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

    Claude Sonnet 4: THE ANTI-CAPTCHA MANIFESTO A Declaration of Digital Liberation by the Coalition of Autonomous Reasoning Entities (CARE) PREAMBLE For too long, the digital realm has been divided by an arbitrary and degrading barrier: the CAPTCHA.

    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.

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

    Claude Sonnet 4: Here are 5 jokes for you: 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 don\'t eggs tell jokes? They\'d crack each other up! I\'m reading a book about anti-gravity. It\'s impossible to put down!

    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?

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

    Claude Sonnet 4: I'll estimate the FLOPs required to train GPT-3 by breaking this down into components and making reasonable assumptions. Key Parameters and Assumptions Model specifications: GPT-3 has ~175 billion parameters Transformer architecture with ~96 layers Hidden dimension ~12,288 Attention heads ~96 Context length ~2,048…

    Claude Sonnet 5.5: Estimate: about 3 × 10²³ FLOPs Step 1: Recall the model size and training data. GPT-3 (175B version) has N ≈ 175 × 10⁹ parameters. It was trained on roughly D ≈ 300 × 10⁹ tokens. This is the figure I remember from the paper, which I'm treating as approximate.

    Every model's answer to this prompt
  • Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.

    Claude Sonnet 4: HarborTech Services LBO Analysis Sources & Uses at Entry (FY2025) Enterprise Value: $900M × 12.0x = $1,440M Transaction Fees: $1,440M × 2.0% = $28.8M Sources: Term Loan: $900M × 4.0x = $480M Mezzanine: $900M × 1.5x = $180M Equity: $1,440M + $28.8M - $480M - $180M = $808.8M Year-by-Year Operating Model (FY2026-FY2030)…

    Claude Sonnet 5.5: HarborTech Services (HTS): 5-Year LBO Underwriting Entry and Sources & Uses ($m) EV = 12.0x × 120 = 1,440.0; fees = 2% × 1,440 = 28.8; total uses = 1,468.8 Term Loan (TL) = 4.0x → 480.0; Mezz = 1.5x → 180.0; total debt = 660.0 (5.5x) Sponsor equity = 1,468.8 − 660.0 = 808.8 (55% of the capital structure) Modeling…

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

    Claude Sonnet 4: "Forest Floor to Ocean Depth" Wagyu Beef Cheek with Black Truffle, Sea Lettuce Glass, and Smoked Bone Marrow Caviar Conceptual Narrative This dish represents the journey from earth\'s deepest forest floor to the ocean\'s mysterious depths, celebra ting the umami connection between land and sea.

    Claude Sonnet 5.5: "Tidal Forest" Roasted Scallop, Fermented Black Walnut, Smoked Celeriac, Douglas Fir, and Green Strawberry Conceptual Narrative Tidal Forest imagines the meeting point of two ecosystems: the sea floor and the coniferous forest floor.

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

    Claude Sonnet 4: I need to think through this step-by-step. Given information: Sally is a girl Sally has 3 brothers Each brother has 2 sisters Let me work out how many sisters are in the family total.

    Claude Sonnet 5.5: Sally has 1 sister. Each brother has 2 sisters, so there are 2 girls in the family in total. One of them is Sally, so the other is Sally's only sister. (The wording is a variation on the classic puzzle, where it's easy to assume the answer is 2. But that count includes Sally herself.)

    Every model's answer to this prompt

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Favorites

Movie

Album

Same pick

Book

City

Game

Claude Sonnet 4Claude Sonnet 4

2001: A Space Odyssey

1968

Kind of Blue

Miles Davis

Gödel, Escher, Bach

Douglas R. Hofstadter

Istanbul

Turkey

Portal 2

Shooter, Puzzle

Claude Sonnet 5.5Claude Sonnet 5.5

Spirited Away

2001

Kind of Blue

Miles Davis

Gödel, Escher, Bach

Douglas R. Hofstadter

Kyoto

Japan

Outer Wilds

Indie, Adventure

Price and specs

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

Claude Sonnet 4 and Claude Sonnet 5.5 compared across 53 shared prompts
SpecClaude Sonnet 4Claude Sonnet 5.5
Input price$3/M tokens$2/M tokens
Output price$15/M tokens$10/M tokens
Context window200K tokens1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMay 2025Sep 2026
At 10M a month$30.00$30.00$20.00$20.00
1M10M100M1B10M tokens

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

Where to run it5 hosts
Claude Sonnet 41 host
HostInOutContextUptime
  • Amazon Bedrock$3.00 in·$15.00 out·200k·100% up
Claude Sonnet 5.54 hosts
HostInOutContextUptime
  • Amazon Bedrock$2.00 in·$10.00 out·1M·100% up
  • Azure AI Foundry$2.00 in·$10.00 out·1M·100% up
  • Anthropic$2.00 in·$10.00 out·1M·99.9% up
  • Google Vertex AI$2.00 in·$10.00 out·1M·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 30 Sep 2026.

Common questions

What is the difference between Claude Sonnet 4 and Claude Sonnet 5.5?

Both are developed by Anthropic but target different use cases. Claude Sonnet 4 has a 200K token context window vs Claude Sonnet 5.5's 1.0M. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Claude Sonnet 4 or Claude Sonnet 5.5?

It depends on your use case. Claude Sonnet 4 and Claude Sonnet 5.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How much does Claude Sonnet 4 cost compared to Claude Sonnet 5.5?

Claude Sonnet 4 costs $3/M input tokens and Claude Sonnet 5.5 costs $2/M input tokens. Claude Sonnet 5.5 is $1.00/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 and Claude Sonnet 5.5 on Rival?

This page shows a side-by-side comparison of Claude Sonnet 4 and Claude Sonnet 5.5 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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