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  5. GPT-6 LunavsKimi K3
Updated Sep 2026

GPT-6 LunavsKimi K3

GPT-6 Luna is cheaper than Kimi K3 at $0.1/M vs $3/M input tokens.

GPT-6 Luna and Kimi K3 compared across 20 shared prompts
SpecGPT-6 LunaKimi K3
Input price$0.1/M tokens$3/M tokens
Output price$0.5/M tokens$15/M tokens
Context window1.1M tokens1.0M tokens
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedSep 2026Jul 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 20 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-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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Kimi K31,904 words
Contract Risk Analysis: Contractor Perspective Overall assessment: Every substantive clause in this agreement is one-sided in the Client's favor. Several are likely unenforceable as written, but enforceability only matters after expensive litigation — the practical risk is that these clauses give the Client leverage to…
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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-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 K31,296 words
The Decision First I'm disclosing. Not because I'm choosing ethics over shareholder value, but because concealment is the value-destroying path on every axis — legal, financial, and human.
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Advanced Investment Memo (IC Memo)

You are writing an internal investment committee memo for a long/short equity fund. Company (fictional): LedgerLift (ticker: LLLT) – B2B…

GPT-6 Luna896 words
LedgerLift (LLLT) — Investment Committee Memo Recommendation: Short 12-month price target: $28–$42 At $46, LedgerLift’s price implies continued strong growth and margin expansion; our DCF scenarios value the shares at approximately $17–$42, with the base case near $28.
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Kimi K31,055 words
IC MEMO — LedgerLift (LLLT) Price $46 Mkt cap $8.74B Net cash $1.4B EV $7.34B EV/FY25 Rev 9.0x EV/FY26E Rev 7.4x EV/FY26E EBIT 37x Recommendation: SHORT (moderate conviction; 1.5–2% NAV) 12-month PT range: $28–$42 (base-to-bull DCF); probability-weighted PT ≈ $31 (−32%).
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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-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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Kimi K3785 words
The 3 Weakest Claims in MindMeld AI's Pitch "94% accuracy decoding neural patterns into text... any language" (Slide 3) Why it's weak: This claim exceeds the published state of the art — including invasive systems — by a wide margin.
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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-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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Kimi K31,167 words
The 3-Month Longevity Optimization Protocol Important caveat before we begin: This plan is designed for a healthy adult. Get physician clearance before starting—especially for prolonged fasting, high-dose supplements, and anything prescription-grade. Several items below interact with medications (notably berberine).
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Michelin Star Recipe Design

Design an innovative recipe for a multi-component dish worthy of a Michelin 3-star restaurant. The recipe should feature an unusual…

GPT-6 Luna1,249 words
Turbot, White Asparagus, Green Strawberry Kosho & Toasted-Hay Beurre Blanc A composed spring dish for four, built around an unusual pairing: tart green strawberry and toasted hay.
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Kimi K31,229 words
FIRST FROST Langoustine · Frost-Sweetened Parsnip · Coffee · Vanilla · Horseradish Snow The Narrative This dish is built on a piece of winter biochemistry. When the first frost strikes, parsnips and horseradish defend themselves by converting starch into sugar — a natural antifreeze — which is why country cooks have…
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Our Verdict
GPT-6 Luna
GPT-6 Luna
Kimi K3
Kimi K3

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

GPT-6 Luna costs 30x 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
30× cheaper
Output
$0.50
30× cheaper
Kimi K3
Input
$3.00
Output
$15.00

GPT-6 Luna is cheaper on both: 30× input, 30× output.

Where to run it

20 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 K317 hosts
HostInOutContextUptime
SSail Researchfp4$0.88 in·$10.53 out·1M·99.3% upIInferenceNetfp4$1.30 in·$11.40 out·1M·99.8% upWWafer$1.99 in·$15.00 out·1M·98.8% upMMakora$2.04 in·$12.75 out·1M·98.1% upPPhala$2.10 in·$10.50 out·1M·99% upRRelacefp4$2.10 in·$10.50 out·1M·98.1% up
11 more hostsFewer hosts
MMorph$2.50 in·$14.00 out·1M·99.6% upDDigitalOcean$2.55 in·$12.95 out·1M·98.7% upDDeepInfrabf16$2.85 in·$14.25 out·1M·96.6% upBBasetenfp8$3.00 in·$15.00 out·1M·98.8% upCChutesmxfp4$3.00 in·$15.00 out·1M·95.9% upFFireworks$3.00 in·$15.00 out·1M·99.9% upModalmxfp4$3.00 in·$15.00 out·1M·99.8% upMoonshot AImxfp4$3.00 in·$15.00 out·1M·99.9% upPParasailfp4$3.00 in·$15.00 out·1M·98.9% upTTogether$3.00 in·$15.00 out·1M·99.2% upAlibaba Cloud$3.45 in·$17.25 out·1M·99.3% 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 K3 is developed by Moonshot AI. GPT-6 Luna has a 1.1M token context window vs Kimi K3's 1.0M. 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 K3 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 K3 costs $3/M input tokens. GPT-6 Luna is $2.90/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-6 Luna and Kimi K3 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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