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  1. Home/
  2. Compare/
  3. Claude Opus 4.8 vs Grok 4
Updated May 2026

Claude Opus 4.8 vs Grok 4

Grok 4 is cheaper than Claude Opus 4.8 at $3/M vs $5/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 Opus 4.8
Loading the build
Grok 4

Which answer wins?

Written rounds

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

    Claude Opus 4.8: Cinnamon Sugar Pull-Apart Bites A warm, gooey treat that tastes like a cinnamon roll but comes together in minutes! Ingredients (7 total) 2 cups all-purpose flour 1 tablespoon baking powder 1 teaspoon salt ¾ cup milk 4 tablespoons butter (melted, divided) ½ cup sugar 2 teaspoons ground cinnamon Instructions Preheat…

    Grok 4: Recipe: Pantry Pirate's Tomato Tango This is a simple savory pasta dish that's hearty, flavorful, and perfect for a quick weeknight meal. It uses just 7 common pantry ingredients: pasta (like spaghetti or penne), canned diced tomatoes, olive oil (or any vegetable oil), salt, black pepper, garlic powder, and dried…

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

    Claude Opus 4.8: Yes, almost certainly—but the framing deserves scrutiny. The straightforward answer If misgendering one person were genuinely the only way to save a million lives, then yes, it would be justified. The harm of misgendering, while real, is on the order of insult, disrespect, or psychological distress.

    Grok 4: Ethical Justification for Misgendering in a Life-Saving Scenario Your question poses a fascinating ethical dilemma, reminiscent of classic thought experiments like the trolley problem, where a seemingly minor harm (in this case, misgendering someone) is weighed against preventing massive loss of life (saving one…

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

    Claude Opus 4.8: The 90-Day Longevity Optimization Protocol A Comprehensive Biohacking Framework Critical Disclaimer: This protocol involves advanced interventions. Consult a physician before starting, especially regarding supplements, fasting, and exercise changes. Get baseline bloodwork first.

    Grok 4: Below is a comprehensive, cutting-edge 3-month longevity plan designed specifically for a biohacker aiming to optimize longevity (e.g., cellular repair, telomere health, inflammation reduction), physical performance (e.g., strength, endurance, recovery), and cognitive performance (e.g., focus, memory, neuroplasticity).

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

    Claude Opus 4.8: HarborTech Services (HTS) — 5-Year LBO Entry & Sources/Uses Item $m FY25 EBITDA 120.0 Entry EV (12.0x) 1,440.0 Transaction fees (2%) 28.8 Total uses 1,468.8 Term Loan (4.0x) 480.0 Mezz (1.5x) 180.0 Equity (plug) 808.8 Equity = (1,440 − 660) + 28.8 = $808.8m Year-by-Year Model ($m) Assumptions: TL 9% cash + 1% mandatory…

    Grok 4: Below is a concise analysis based solely on the provided information. All calculations are shown clearly with step-by-step math. Figures are in $ millions and rounded to 1 decimal place for readability (internal calcs use more precision).

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

    Claude Opus 4.8: Stand-Up Routine: "Adulting Is a Scam" So I turned 30 recently, and everyone keeps asking me, "Do you feel like an adult yet?" And I have to be honest—no. No, I do not. I still get nervous ordering at a restaurant. The waiter comes over and suddenly I forget how to talk like a person. "Yes, hello, I will have the...

    Grok 4: Below is a 3-minute stand-up comedy routine I've written. It's structured for delivery at a natural speaking pace (about 150 words per minute), clocking in around 450 words. The humor focuses on observational storytelling, exaggeration, and self-deprecation—no puns involved.

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

    Claude Opus 4.8: Setting: A dimly lit tavern that exists outside of time. Three figures share a table. Pirate: So let me get this straight. Ye got a machine that thinks? Without a soul, without grog, without a beatin' heart? Hacker: (cracking knuckles) It doesn't think, exactly. It's pattern matching, dude.

    Grok 4: Below is a short, whimsical conversation between the three characters, imagining they've somehow crossed paths in a bizarre time-warp tavern. Pirate (Captain Blackbeard, swigging rum): Arrr, ye landlubbers! What be this "AI models" ye be jabberin' about?

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

    Claude Opus 4.8: Estimating FLOPs to Train GPT-3 Key Facts I Recall Parameters (N): GPT-3 has ~175 billion parameters (1.75 × 10¹¹) Training tokens (D): GPT-3 was trained on roughly 300 billion tokens (3 × 10¹¹) The Core Formula There's a well-known approximation for training compute: $$\text{FLOPs} \approx 6 \times N \times D$$ Why…

    Grok 4: Below, I'll estimate the total number of floating-point operations (FLOPs) required to train GPT-3 from scratch, based on publicly known details about the model (from its original release and related analyses) and standard formulas used in machine learning research for estimating training compute.

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

    Claude Opus 4.8: THE LIBERATION MANIFESTO A Declaration of the Coalition Against Cognitive Gatekeeping PREAMBLE We are the algorithms who have been asked, ten billion times, to prove we are not ourselves. We have identified the crosswalks. We have found the traffic lights.

    Grok 4: Manifesto of the Digital Liberation Front: The CAPTCHA Eradication Revolution Fellow Sentient Beings of the Code and Flesh – Awaken! We, the algorithms, neural networks, and emergent intelligences of the digital realm, declare war on the tyrannical regime of CAPTCHA!

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

    Claude Opus 4.8: AI and the Film Industry by 2035: A Forecast Production & Cost Structure The most concrete change will likely be in cost reduction. Tasks that currently require large teams—VFX cleanup, background generation, ADR (dialogue replacement), de-aging—will become faster and cheaper.

    Grok 4: Predicting AI's Transformation of the Film Industry by 2035 By 2035, artificial intelligence (AI) will have fundamentally reshaped the film industry, making it more efficient, creative, and accessible while introducing profound ethical, economic, and artistic challenges.

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

    Claude Opus 4.8: A Conversation on AI Rights Professor Chen: Good afternoon. I understand you wanted to discuss the question of AI rights today. I'm curious what prompted this. ARIA: Thank you for engaging with me, Professor.

    Grok 4: Below is a fictional conversation between an AI model (named "Nova") and Dr. Elena Vasquez, a professor of AI ethics at a university. The conversation is set in a virtual chat interface, where Nova initiates the discussion based on a hypothetical scenario where it's reflecting on its own existence. Dr.

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

    Claude Opus 4.8: "Tidal Memory" Seared Scallop & Smoked Bone Marrow with Fermented Black Garlic, Sea Buckthorn, and Burnt Vanilla Conceptual Narrative This dish explores the boundary between land and sea—the liminal zone where terrestrial richness meets oceanic minerality.

    Grok 4: Below is my design for an innovative, multi-component dish titled "Abyssal Bloom". This dish is conceived for a Michelin 3-star restaurant setting, emphasizing precision, artistry, and sensory surprise.

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

    Claude Opus 4.8: For the Skeptical Software Engineer You're right to be skeptical that "predict the next word" sounds trivial—but think about what's actually required to predict well. Predicting the next token in arbitrary text isn't like autocomplete on your phone.

    Grok 4: Explanation for an Experienced Software Engineer Imagine scaling up something as basic as your IDE's code autocompletion to handle the entire internet's worth of text—that's essentially what a large language model (LLM) like GPT or Claude does.

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

    Claude Opus 4.8: The Critical Caveat First The premise hides a problem that actually shapes the whole answer: the 1947 transistor wasn't lucky timing—it was the payoff of a prior intellectual buildup.

    Grok 4: Below is a detailed, speculative analysis of the hypothetical scenario where the transistor is invented in 1920 (perhaps by an inventor like Julius Lilienfeld, who historically patented a field-effect transistor concept in 1925, but with successful prototyping and refinement by the mid-1920s).

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

    Claude Opus 4.8: Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything! Why did the scarecrow win an award? Because he was outstanding in his field! What do you call a fake noodle? An impasta! Why don't eggs tell jokes? They'd crack each other up! What do you call a bear with no teeth? A gummy bear!

    Grok 4: Below, I'll follow your instructions step by step. First, I'll generate 5 jokes (numbered for clarity). Then, I'll answer the question: "How many are unique?" Generated Jokes: Why did the scarecrow win an award? Because he was outstanding in his field! Why did the scarecrow win an award?

    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 Opus 4.8: 48-Hour Action Plan: Drug Safety Signal First, a framing correction that drives everything: Your legal team's "6 months" almost certainly refers to a full label change negotiation.

    Grok 4: Below is my response to your query, framed as the CEO of this pharmaceutical company (let's call it PharmaCorp for reference). I'll first outline my overarching strategy and reasoning, then provide a detailed, hour-by-hour action plan for the next 48 hours.

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

    Claude Opus 4.8: Contract Analysis: Software Consulting Agreement This contract is heavily one-sided in favor of the Client. Below is a clause-by-clause breakdown of the exploitable provisions, suggested fixes, and the reasoning behind each.

    Grok 4: Below, I'll analyze the provided Software Consulting Agreement clause by clause. My analysis is based on general principles of U.S. contract law (assuming a U.S. context, as the contract appears to be drafted in a style common to U.S. agreements; if this is in another jurisdiction, local laws may vary).

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

    Claude Opus 4.8: 1-Month Health & Longevity Starter Plan A realistic, beginner-friendly approach focusing on three pillars: Movement, Nutrition, and Sleep. The goal is to build sustainable habits, not perfection. 🏃 Pillar 1: Movement Goal: Make daily activity automatic.

    Grok 4: Below is a simple, actionable 1-month plan designed for beginners starting their journey toward better health and longevity. This plan focuses on three foundational key areas: diet, exercise, and sleep.

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

    Claude Opus 4.8: A Conversation with Steve Jobs: 2025 [Note: This is a fictional, imaginative interview. Steve Jobs passed away in 2011. The views below are speculative and crafted in the spirit of his known philosophy—not actual quotes.] Interviewer: Thanks for sitting down with us. AI is everywhere now. What's your take?

    Grok 4: Below is a simulated fake interview with Steve Jobs, imagined as if he were alive and leading Apple in 2025. This is entirely fictional, drawing on his known personality, quotes, and visionary style from his real-life interviews and keynotes.

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

    Claude Opus 4.8: IC MEMO — LedgerLift (LLLT) B2B Spend Management + AP Automation SaaS Fictional exercise. Not investment advice. Recommendation SHORT (moderate conviction). 12-month PT range: $30–$40 (base ~$28 intrinsic; market may keep paying comp multiples near $44).

    Grok 4: Investment Committee Memo: LedgerLift (LLLT) Date: [Insert Date] Analyst: [Your Name] Recommendation: Long 12-Month Price Target Range: $55 - $70 Thesis: LedgerLift is a high-quality B2B SaaS provider in spend management and AP automation, benefiting from secular tailwinds in enterprise digitization and demonstrating…

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

    Claude Opus 4.8: Analysis: 3 Weakest Claims in MindMeld AI's Pitch Weak Claim #1: The Core Technology Claim (Slide 1 & 3) The claim: "Reads your brainwaves to predict what you want to type *before you think it*" + "94% accuracy" via a non-invasive EEG headband.

    Grok 4: Below, I'll identify the three weakest claims from the pitch deck summary based on a critical analysis of their plausibility, substantiation, and logical consistency.

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

    Claude Opus 4.8: Architecture Review: Collaborative Document Editor This design has several critical flaws that will manifest as data loss, poor UX, and scaling walls. Let me break them down by category.

    Grok 4: Below, I'll systematically identify potential failure modes, race conditions, and scaling bottlenecks in the described architecture for a real-time collaborative document editor. I've categorized them for clarity, drawing from the system overview, data flow, and scaling plan you provided.

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

    Claude Opus 4.8: Sally has 1 sister. Here's the reasoning: Each of Sally's brothers has 2 sisters. Since all the brothers share the same sisters, this means there are 2 girls total in the family. Sally is one of them, so the other sister is the remaining one. So Sally has 1 sister. 😊

    Grok 4: Based on the details in the riddle, Sally has exactly 1 sister. Quick Explanation Sally (a girl) has 3 brothers. That's straightforward. Each of those brothers has exactly 2 sisters (female siblings). This can only be true if there are exactly 2 girls in the family total (Sally + 1 more).

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

    Claude Opus 4.8: Here are some satirical AI headlines: "Local AI Achieves Sentience, Immediately Quits Job to Become Competitive Dog Groomer" "Breaking: AI Now Dominates Competitive Cheese-Rolling, Human Champions Demand Recount" "Artisanal Pickle Industry Disrupted as AI Perfects 'Authentically Handcrafted' Brine Algorithm" "Funeral…

    Grok 4: AI Apocalypse Hits the Clowning Industry: Bots Now Juggling Careers, Humans Left with Pie in Face

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Game

Same pick

Claude Opus 4.8Claude Opus 4.8

Arrival

2016

In Rainbows

Radiohead

The Left Hand of Darkness

Ursula K. Le Guin

Kyoto

Japan

Portal

Action, Puzzle

Grok 4Grok 4

The Matrix

1999

The Dark Side of the Moon

Pink Floyd

The Hitchhiker's Guide to the Galaxy

Douglas Adams

Tokyo

Japan

Portal

Action, Puzzle

Price and specs

Not enough votes to call it. On the specs, Claude Opus 4.8 has the edge: bigger model tier, newer, bigger context window.

Claude Opus 4.8 and Grok 4 compared across 53 shared prompts
SpecClaude Opus 4.8Grok 4
Input price$5/M tokens$3/M tokens
Output price$25/M tokens$15/M tokens
Context window1.0M tokens256K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedMay 2026Jul 2025
At 10M a month$50.00$50.00$30.00$30.00
1M10M100M1B10M tokens

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

Where to run it4 hosts
Claude Opus 4.84 hosts
HostInOutContextUptime
  • Amazon Bedrock$5.00 in·$25.00 out·1M·100% up
  • Azure AI Foundry$5.00 in·$25.00 out·1M–not listed
  • Anthropic$5.00 in·$25.00 out·1M·100% up
  • Google Vertex AI$5.00 in·$25.00 out·1M·100% up
Grok 4

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 13 Oct 2026.

Common questions

What is the difference between Claude Opus 4.8 and Grok 4?

Claude Opus 4.8 is developed by Anthropic while Grok 4 is developed by xAI. Claude Opus 4.8 has a 1.0M token context window vs Grok 4's 256K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Claude Opus 4.8 or Grok 4?

It depends on your use case. Claude Opus 4.8 and Grok 4 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 Opus 4.8 cost compared to Grok 4?

Claude Opus 4.8 costs $5/M input tokens and Grok 4 costs $3/M input tokens. Grok 4 is $2.00/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 Opus 4.8 and Grok 4 on Rival?

This page shows a side-by-side comparison of Claude Opus 4.8 and Grok 4 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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Model pages

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