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  5. GPT-6 LunavsKimi K2
Updated Sep 2026

GPT-6 LunavsKimi K2

GPT-6 Luna is cheaper than Kimi K2 at $0.1/M vs $0.57/M input tokens.

GPT-6 Luna and Kimi K2 compared across 20 shared prompts
SpecGPT-6 LunaKimi K2
Input price$0.1/M tokens$0.57/M tokens
Output price$0.5/M tokens$2.3/M tokens
Context window1.1M tokens—
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedSep 2026Jul 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 20 prompts both answered. Formatting stripped, words untouched.

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-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…
Read the full answer
Kimi K2247 words
Caramel-Cloud Banana Skillet Cake (aka “The One-Bowl Wonder that Tastes Like Sunday Morning”) Ingredients (all everyday staples) 2 very ripe bananas 1 cup all-purpose flour ½ cup granulated sugar 1 large egg ¼ cup milk (any kind) 3 Tbsp butter (or neutral oil) ½ tsp baking powder Pinch of salt is nice but…
Read the full answer

Adversarial Contract Review

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

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.
Read the full answer
Kimi K21,204 words
Foundational disclaimer: I am not your lawyer, this is not legal advice, and you should retain qualified counsel before signing or revising any contract. The comments below are purely educational and based on U.S.–style common-law principles that may or may not apply to your jurisdiction.
Read the full answer

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-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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Kimi K2657 words
1-MONTH STARTER PLAN FOR HEALTH & LONGEVITY (Do-able without special gear, drastic diets, or big time blocks) Keep the same 3 focus areas for the whole month so you can build a habit loop. Goal: finish the month feeling “I can keep this up” instead of “I’m exhausted.”
Read the full answer

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-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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Kimi K2702 words
48-Hour CEO Action Plan: Balancing Patient Safety, Ethics, and Business Survival Core Principles: Patient safety overrides all other interests. Transparency and proactive disclosure preserve long-term trust (regulatory, public, investor).
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Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

GPT-6 Luna1,472 words
The most important caveat is that inventing a transistor is not the same as inventing the modern semiconductor industry. A device demonstrated in 1920 might be a crude, low-power, unreliable point-contact transistor.
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Kimi K2554 words
Thought Process: To explore the implications of an earlier transistor invention (1920 vs. 1947), we need to analyze cascading effects across multiple domains. Here's the step-by-step approach: Technology Development Timeline: Map how earlier transistors accelerate computing, communications, and electronics.
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Explain Like I'm a Specific Expert

Explain how a large language model (like GPT or Claude) learns and generates text to each of these three audiences: 1. **An experienced…

GPT-6 Luna672 words
For an experienced software engineer A language model is trained on many text sequences, split into tokens—roughly word fragments, not necessarily whole words. During training, it repeatedly sees a prefix and tries to predict the next token.
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Kimi K2682 words
────────────────── Software Engineer ────────────────── Think of the model as a distributed cache of compressed program traces. During training, every sentence in the crawl is treated like a log line produced by an unobserved deterministic program that the model is trying to reverse-engineer.
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Our Verdict
GPT-6 Luna
GPT-6 Luna
Kimi K2
Kimi K2

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

GPT-6 Luna costs 4.6x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-6 Luna
Input
$0.10
5.7× cheaper
Output
$0.50
4.6× cheaper
Kimi K2
Input
$0.57
Output
$2.30

GPT-6 Luna is cheaper on both: 5.7× input, 4.6× output.

Where to run it

4 hosts, cheapest first

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
Kimi K21 host
HostInOutContextUptime
NNovitafp8$0.57 in·$2.30 out·131k·100% up

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

Research

What we learned reading every model

FAQ

Common questions

GPT-6 Luna is developed by OpenAI while Kimi K2 is developed by Moonshot AI. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-6 Luna and Kimi K2 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 20 challenges so you can judge which fits your needs best.

GPT-6 Luna costs $0.1/M input tokens and Kimi K2 costs $0.57/M input tokens. GPT-6 Luna is $0.47/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-6 Luna and Kimi K2 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-6 Luna logo
GPT-6 Luna20 outputs, specs and price
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Rival
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