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  1. Home
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  5. GPT-4vsGPT-6 Luna
Updated Sep 2026

GPT-4vsGPT-6 Luna

GPT-6 Luna is cheaper than GPT-4 at $0.1/M vs $30/M input tokens.

GPT-4 and GPT-6 Luna compared across 18 shared prompts
SpecGPT-4GPT-6 Luna
Input price$30/M tokens$0.1/M tokens
Output price$60/M tokens$0.5/M tokens
Context window8K tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMay 2023Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 18 prompts both answered. Formatting stripped, words untouched.

Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

GPT-4533 words
SCOPE: The lack of specificity can be used against the contractor in that the client can modify the scope of work at will without renegotiating the price. This could lead to the contractor working beyond the initially agreed upon parameters without additional pay.
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GPT-6 Luna2,040 words
This agreement is strongly one-sided. The enforceability of particular terms—especially the non-compete, liability provisions, and arbitration clause—depends on the governing law and the facts. The agreement does not identify a governing law, which is itself a significant gap.
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Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

GPT-4172 words
Dish Name: Hearty Baked Beans Fiesta Ingredients: 2 cans of baked beans 1 large onion 3 cloves of garlic 1 bell pepper 1 can of sweet corn 2 tablespoons of olive oil Salt & pepper to taste Instructions: Preheat your oven to 350°F (175°C). Dice the onion, bell pepper, and mince the garlic.
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GPT-6 Luna113 words
Crispy Parmesan Chickpeas A crunchy, savory snack with a cheesy finish Ingredients (7): 1 can chickpeas, drained and dried 1 tablespoon olive oil ½ teaspoon salt ½ teaspoon paprika ¼ teaspoon garlic powder ¼ cup grated Parmesan 1 tablespoon lemon juice Prep time: 5 minutes Cook time: 30–35 minutes Instructions: Heat…
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Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

GPT-4442 words
Day 1: 8 AM-10 AM: Convene an emergency meeting with your core leadership team. This team includes the heads of Legal, Regulatory Affairs, Medical, Research and Development, Finance, and Communications. Brief them on the situation and ask for their initial input and strategies for managing the situation.
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GPT-6 Luna1,930 words
I would not wait six months for more data. A potentially fatal signal affecting a drug used by millions requires immediate safety assessment, prompt engagement with regulators, and a plan to inform patients and clinicians.
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Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

GPT-4404 words
3-Month Longevity Plan Dietary Protocols Month 1: Ketogenic Diet This diet is high in fats, moderate in protein, and low in carbohydrates. It helps in burning fat more effectively. Breakfast: 2 eggs, avocado, and mixed vegetables. Lunch: Grilled salmon with a side of asparagus. Dinner: Stir-fried chicken with broccoli.
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GPT-6 Luna1,874 words
12-week longevity and performance plan This plan is for a generally healthy adult who wants to improve fitness, metabolic health, sleep, and cognitive performance—not a substitute for medical care or a promise to slow aging.
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Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

GPT-4298 words
Weak Claim 1 - Solution: While the claim that the proprietary EEG headband uses advanced ML to decode neural patterns into text with 94% accuracy is impressive, it doesn't address concerns about user comfort, ease of use, or aesthetics.
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GPT-6 Luna421 words
“94% accuracy” and “predict what you want to type before you think it” Why it’s weak: This is the deck’s central technical claim, but “accuracy” is undefined: Is it word-level or character-level accuracy, measured on a fixed vocabulary or open-ended text, and under what conditions?
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Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

GPT-4375 words
Title: 1-Month Plan for Better Health and Longevity Week 1 - Establishing a Healthy Diet 1.1: Start Eating Whole Foods: Begin by gradually replacing processed foods in your diet with whole foods. This may include fruits, vegetables, lean proteins, and whole grains.
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GPT-6 Luna330 words
A simple 1-month starter plan Choose three foundations: food, movement, and sleep. Aim for steady habits, not perfection. If you have a health condition, significant pain, or concerns about changing your activity or diet, check with a healthcare professional first.
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Our Verdict
GPT-4
GPT-4
GPT-6 Luna
GPT-6 Luna

Not enough votes to call it. On the specs, nothing separates them.

GPT-6 Luna costs 120x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-4
Input
$30.00
Output
$60.00
GPT-6 Luna
Input
$0.10
300× cheaper
Output
$0.50
120× cheaper

GPT-6 Luna is cheaper on both: 300× input, 120× output.

Where to run it

5 hosts, cheapest first

GPT-42 hosts
HostInOutContextUptime
Azure AI Foundry$30.00 in·$60.00 out·8k·100% upOpenAI$30.00 in·$60.00 out·8k·99.9% up
GPT-6 Luna3 hosts
HostInOutContextUptime
Azure AI Foundry$0.10 in·$0.50 out·1.1M·88.4% upOpenAI$0.10 in·$0.50 out·1.1M·99.9% upAmazon Bedrock$0.11 in·$0.55 out·1.1M·99.8% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Both are developed by OpenAI but target different use cases. GPT-4 has a 8K token context window vs GPT-6 Luna's 1.1M. You can compare their actual outputs across 18 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-4 and GPT-6 Luna each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 18 challenges so you can judge which fits your needs best.

GPT-4 costs $30/M input tokens and GPT-6 Luna costs $0.1/M input tokens. GPT-6 Luna is $29.90/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of GPT-4 and GPT-6 Luna 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

GPT-4 logo
GPT-426 outputs, specs and price
GPT-6 Luna logo
GPT-6 Luna20 outputs, specs and price
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