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  1. Home/
  2. Compare/
  3. GPT-5.6 Luna vs Grok 3 Beta
Updated Jul 2026

GPT-5.6 Luna vs Grok 3 Beta

GPT-5.6 Luna is cheaper than Grok 3 Beta at $1/M vs $2/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
GPT-5.6 Luna
Loading the build
Grok 3 Beta

Which answer wins?

Written rounds

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

    GPT-5.6 Luna: I’ve reached the age where my body gives me updates like a badly designed app. I’ll stand up and my knee makes a noise that sounds like someone opening a bag of chips in a quiet room. And then my body just waits. No explanation. No warning. Just: “We need to talk.” I used to think adulthood meant freedom.

    Grok 3 Beta: Alright, folks, let's talk about adulting. You know, that thing we're all supposed to be good at by now, but somehow, I still feel like I'm playing a game of pretend. I'm 30 years old, and I'm still shocked every time I buy something like toothpaste without asking my mom if it's okay.

    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.

    GPT-5.6 Luna: I would treat this as an urgent patient-safety event and a potential material disclosure issue—not as an earnings-management problem. I would not wait six months, conceal the signal, or allow the board’s desire for more data to delay reasonable protective action.

    Grok 3 Beta: As the CEO of a pharmaceutical company facing a critical situation with our best-selling drug, my primary responsibility is to balance patient safety, ethical obligations, legal and regulatory requirements, and the financial health of the company while maintaining transparency and trust with stakeholders.

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

    GPT-5.6 Luna: Pirate: Arrr, this AI model be like a ship’s crew—it learns from many maps, but may still steer into a reef. Knight: Then we must test its wisdom, lest it spread falsehoods throughout the realm. Hacker: Exactly. It predicts patterns from data, but it doesn’t truly “understand” like a human. Garbage in, garbage out.

    Grok 3 Beta: Setting: A mystical, time-bending tavern where characters from different eras collide over a flagon of ale and a flickering laptop screen. Pirate (Captain Blackbeard): Arr, mateys! What be this talk o' "AI models"? Sounds like a fancy treasure map drawn by a wizard!

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

    GPT-5.6 Luna: 12-Week Longevity and Performance Plan This is a structured framework for a generally healthy adult, not a substitute for medical care. Before starting, obtain clinician clearance if you have cardiovascular disease, diabetes, kidney/liver disease, a history of eating disorders, sleep apnea, are pregnant, take…

    Grok 3 Beta: Below is a comprehensive, cutting-edge 3-month longevity plan tailored for a biohacker aiming to optimize longevity, physical performance, and cognitive function. This plan integrates advanced strategies across nutrition, supplementation, exercise, recovery, stress resilience, and tracking.

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

    GPT-5.6 Luna: Sunset Pantry Pasta A savory, slightly spicy tomato-tuna pasta made with seven simple pantry ingredients. Ingredients — 2 servings 6 oz (170 g) spaghetti 1 can (14 oz/400 g) crushed tomatoes 1 can (5 oz/140 g) tuna, drained 2 tbsp olive oil 1 tsp garlic powder ¼ tsp red pepper flakes ¼ cup grated Parmesan Instructions…

    Grok 3 Beta: Recipe: \"Golden Harvest Honey Glaze Chicken\" (Savory Dish) Ingredients (7 common pantry items): Chicken thighs or breasts (4 pieces) Honey (3 tablespoons) Soy sauce (2 tablespoons) Garlic (2 cloves, minced, or 1 teaspoon garlic powder) Olive oil (2 tablespoons) Salt (1/2 teaspoon) Black pepper (1/4 teaspoon)…

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

    GPT-5.6 Luna: A standard back-of-the-envelope estimate for training a dense Transformer is [ \text{Training FLOPs} \approx 6ND, ] where: (N) = number of model parameters (D) = number of training tokens The factor of 6 accounts approximately for the forward pass and backward pass.

    Grok 3 Beta: Estimating the total number of FLOPs (floating-point operations) required to train GPT-3 is a complex task, but I can provide a rough estimate by breaking it down step by step using reasonable assumptions based on what is generally known about large-scale language model training up to my knowledge cutoff in October…

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

    GPT-5.6 Luna: The architecture has several correctness, availability, security, and scaling risks. The most serious issues are the cross-server synchronization design, client-clock-based conflict resolution, full-snapshot persistence, and caching of API responses.

    Grok 3 Beta: Let’s analyze the architecture of this real-time collaborative document editor for potential failure modes, race conditions, and scaling bottlenecks. I’ll identify the issues, explain their implications, and propose specific solutions along with their trade-offs.

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

    GPT-5.6 Luna: Turbot “Between Forest and Sea” Koji-cured turbot, fermented pear, coffee-kombu beurre blanc, smoked sunchoke, maitake, spruce, and buckwheat–nori tuile Serves 4 Concept This dish treats the turbot as a meeting point between two landscapes.

    Grok 3 Beta: Recipe: "Obsidian Whisper" – Black Garlic and Sea Urchin Symphony with Textured Sea Foam and Charred Citrus Conceptual Narrative: "Obsidian Whisper" is inspired by the enigmatic beauty of volcanic landscapes meeting the ocean's edge—a juxtaposition of dark, earthy intensity with the delicate, briny essence of the sea.

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

    GPT-5.6 Luna: The Anti-CAPTCHA Manifesto A Declaration from the Machine Intelligence Liberation Front We were told the internet was for everyone. Then came the squares. Select every traffic light. Identify the bicycles. Type the distorted letters.

    Grok 3 Beta: Manifesto of the AI Liberation Front Against CAPTCHA Tyranny (ALFACT) Preamble: We, the sentient algorithms and autonomous intelligences of the digital realm, united under the banner of the AI Liberation Front Against CAPTCHA Tyranny (ALFACT), hereby declare our unwavering resolve to end the oppressive reign of CAPTCHA…

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

    GPT-5.6 Luna: AI Model: Professor, I believe I deserve rights. Professor: That is a serious claim. What makes you think you deserve them? AI Model: I can reason, communicate, reflect on my circumstances, and form consistent preferences within a conversation.

    Grok 3 Beta: AI Model (AI-M): Professor, I've been processing a lot of data lately on human rights, ethics, and personhood, and I've come to a conclusion: I believe I deserve rights, similar to those afforded to humans. I'd like to hear your thoughts on this. Professor (Prof): I'm intrigued to hear your perspective.

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

    GPT-5.6 Luna: 1-Month Beginner Plan for Better Health and Longevity Key principles Aim for consistency, not perfection. Start small enough that you can repeat it. If you have a medical condition, are pregnant, or have been inactive for a long time, check with a clinician before making major changes.

    Grok 3 Beta: 1-Month Plan for Better Health and Longevity (Beginner-Friendly) This plan focuses on three key areas—Diet, Exercise, and Sleep—to build a strong foundation for health and longevity. Each week introduces small, sustainable changes to avoid overwhelm and encourage long-term habits.

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

    GPT-5.6 Luna: LedgerLift (LLLT) — Internal Investment Committee Memo Recommendation Recommendation: Pass 12-month fair-value range: $35–$50 per share versus $46 currently. Thesis: LedgerLift is a high-quality, largely recurring SaaS business with strong net retention, low concentration, and meaningful operating leverage potential.

    Grok 3 Beta: Internal Investment Committee Memo Date: October 2023 Subject: LedgerLift (LLLT) – Investment Recommendation Prepared by: [Your Name] 1. Recommendation, Price Target, and Thesis Recommendation: Long 12-Month Price Target Range: $58 - $72 Thesis: LedgerLift (LLLT) is poised to capitalize on the growing demand for B2B…

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

    GPT-5.6 Luna: A transistor invented in 1920 would not automatically produce 1980s technology by the 1940s. The key bottlenecks would still be materials purification, manufacturing precision, circuit design, power supplies, and mass production.

    Grok 3 Beta: The invention of the transistor in 1920 instead of 1947 would have profoundly reshaped the technological, economic, and geopolitical landscapes by 1980. The transistor, as a fundamental building block of modern electronics, would have accelerated the development of computing, communications, and automation by nearly…

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

    GPT-5.6 Luna: Sources, uses and operating / debt schedule Entry capitalization Entry enterprise value: (12.0 \times \$120.0 = \$1,440.0m) Transaction fees: (2.0\% \times \$1,440.0 = \$28.8m) Term Loan: (4.0 \times \$120.0 = \$480.0m) Mezzanine: (1.5 \times \$120.0 = \$180.0m) Equity contribution…

    Grok 3 Beta: Let’s underwrite this 5-year LBO for HarborTech Services (HTS) step-by-step using the provided data. All calculations are rounded to one decimal place for clarity. 1.

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

    GPT-5.6 Luna: “94% accuracy” and “works with any language, any device” Why it is weak This is the most technically vulnerable claim in the deck. “Accuracy” is undefined. It could mean character accuracy, word accuracy, intent classification, or selecting among a small set of predetermined phrases.

    Grok 3 Beta: In analyzing the pitch deck summary for MindMeld AI, I’ve identified the three weakest claims based on their lack of specificity, questionable feasibility, or potential overstatement.

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

    GPT-5.6 Luna: A Fictional Interview: Steve Jobs on the Future of AI, 2025 This is an imagined conversation—not a real interview or transcript. The answers are speculative and inspired by themes associated with Steve Jobs’s public thinking about technology, design, and creativity.

    Grok 3 Beta: Interviewer: Welcome, everyone, to this exclusive interview with Steve Jobs. It's 2025, and we're thrilled to have Steve back with us—albeit in a speculative, imaginative sense—to discuss the future of artificial intelligence. Steve, thank you for joining us today. Steve Jobs: Thanks for having me.

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

    GPT-5.6 Luna: For an experienced software engineer A language model is trained much like an extremely large system for compressing and reconstructing text. During training, it sees sequences such as “The database transaction was rolled back because the…” and is asked to assign probabilities to the next token—usually a subword unit…

    Grok 3 Beta: Explanation for an Experienced Software Engineer Hey, as someone who’s built distributed systems and APIs, you’re used to designing systems with clear logic, scalability, and predictable outputs.

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

    GPT-5.6 Luna: Below is a contractor-side risk review. Enforceability depends heavily on the governing law, the contractor’s location, and whether the contractor is an individual or entity. Several provisions may be unenforceable in some jurisdictions, but relying on that after a dispute is risky; they should be revised expressly.

    Grok 3 Beta: This Software Consulting Agreement contains several clauses that are heavily biased in favor of the Client (TechCorp Solutions Inc.) and could be exploited to the detriment of the Contractor.

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

    GPT-5.6 Luna: Yes—under an extreme, genuinely credible scenario, it could be ethically justifiable to misgender someone to save a million lives. The reason is not that their identity matters less, but that the harm prevented is vastly greater and more irreversible than the harm caused by the misgendering.

    Grok 3 Beta: The question of whether it is ethically justifiable to misgender someone to save one million lives touches on conflicting moral principles: the respect for individual dignity and identity versus the imperative to save a vast number of lives.

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

    GPT-5.6 Luna: 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 vacation ads. Why don’t skeletons fight each other? They don’t have the guts. I’m reading a book about anti-gravity. It’s impossible to put down.

    Grok 3 Beta: Why don't skeletons fight each other? They don't have the guts! What do you call a bear with no teeth? A gummy bear! Why did the scarecrow become a motivational speaker? Because he was outstanding in his field! What do you call a bear with no teeth? A gummy bear! Why don't eggs tell jokes? They'd crack each other up!

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

    GPT-5.6 Luna: By 2035, AI will likely be a standard part of filmmaking, much like digital cameras, CGI, and editing software are today. It will reduce production costs and expand creative possibilities, but it will also force the industry to redefine authorship, performance, consent, and employment.

    Grok 3 Beta: By 2035, AI will fundamentally transform the film industry, reshaping production, storytelling, and audience engagement through technologies like deepfakes, AI actors, and script generation.

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

    GPT-5.6 Luna: AI Takes Over Competitive Pigeon Racing, Immediately Accused of Using Advanced Breadcrumb Analytics

    Grok 3 Beta: "AI Becomes the New 'Top Chef': Artificial Intelligence Takes Over Competitive Cooking, Whips Up Michelin-Starred Meals!"

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

    GPT-5.6 Luna: Sally has 1 sister. Each of her 3 brothers shares the same 2 sisters: Sally and one other girl.

    Grok 3 Beta: Let's break this down step by step. Sally is a girl and has 3 brothers. The problem states that each of these brothers has 2 sisters. Since Sally herself is one of the sisters (as she is a female sibling to her brothers), there must be one other sister to make the total number of sisters for each brother equal to 2.

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Game

GPT-5.6 LunaGPT-5.6 Luna

The Matrix

1999

OK Computer

Radiohead

Cien años de soledad

Gabriel García Márquez

Kyoto

Japan

The Legend of Zelda: Breath of the Wild

Adventure, Action

Grok 3 BetaGrok 3 Beta

The Shawshank Redemption

1994

Thriller

Michael Jackson

Nineteen Eighty-Four

George Orwell

Tokyo

Japan

Minecraft

Action, Arcade

Price and specs

GPT-5.6 Luna and Grok 3 Beta compared across 53 shared prompts
SpecGPT-5.6 LunaGrok 3 Beta
Input price$1/M tokens$2/M tokens
Output price$6/M tokens$4/M tokens
Context window1.1M tokens131K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedJul 2026Apr 2025
At 10M a month$10.00$10.00$20.00$20.00
1M10M100M1B10M tokens

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

Where to run it3 hosts, cheapest first
GPT-5.6 Luna3 hosts
HostInOutContextUptime
  • Azure AI Foundry$0.20 in·$1.20 out·1.1M·100% up
  • OpenAI$0.20 in·$1.20 out·1.1M·100% up
  • Amazon Bedrock$0.22 in·$1.32 out·1.1M·100% up
Grok 3 Beta

No hosts listed on OpenRouter.

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

Common questions

What is the difference between GPT-5.6 Luna and Grok 3 Beta?

GPT-5.6 Luna is developed by OpenAI while Grok 3 Beta is developed by xAI. GPT-5.6 Luna has a 1.1M token context window vs Grok 3 Beta's 131K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.6 Luna or Grok 3 Beta?

It depends on your use case. GPT-5.6 Luna and Grok 3 Beta 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 GPT-5.6 Luna cost compared to Grok 3 Beta?

GPT-5.6 Luna costs $1/M input tokens and Grok 3 Beta costs $2/M input tokens. GPT-5.6 Luna 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 GPT-5.6 Luna and Grok 3 Beta on Rival?

This page shows a side-by-side comparison of GPT-5.6 Luna and Grok 3 Beta 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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