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  5. Claude Opus 5vsGPT-6 Luna
Updated Sep 2026

Claude Opus 5vsGPT-6 Luna

GPT-6 Luna is cheaper than Claude Opus 5 at $0.1/M vs $5/M input tokens.

Claude Opus 5 and GPT-6 Luna compared across 20 shared prompts
SpecClaude Opus 5GPT-6 Luna
Input price$5/M tokens$0.1/M tokens
Output price$25/M tokens$0.5/M tokens
Context window1.0M tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedJul 2026Sep 2026
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…

Claude Opus 5413 words
Midnight Crunch Spaghetti Garlicky olive-oil pasta with toasty golden breadcrumbs — the noise it makes when you eat it is half the pleasure. Prep: 5 minutes Cook: 15 minutes Total: 20 minutes Serves: 2 generously Ingredients (7) 8 oz spaghetti (or any long pasta) ⅓ cup olive oil 6 cloves garlic, thinly sliced ½ tsp red…
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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…

Claude Opus 52,021 words
Crisis Response Plan: Hepatotoxicity Signal Framing note up front: I'm treating this as a US/FDA-regulated situation. Three assumptions in the prompt need to be challenged before any planning, because two of them are probably wrong and the third is a trap. The Three Reframes That Drive Everything 1.
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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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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…

Claude Opus 53,399 words
PETRICHOR Langoustine · Sunchoke · Coffee · Oyster · Lovage Course 7 of 14 — served at the table with an aroma stone I. THE NARRATIVE Petrichor is the smell of the first rain on dry earth.
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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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Adversarial Contract Review

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

Claude Opus 53,428 words
Contract Risk Review: TechCorp Solutions Software Consulting Agreement Bottom line: This is a one-sided template. Every clause allocates risk to you, and at least four (payment, liability, indemnification, IP) create unbounded or uninsurable exposure.
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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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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.…

Claude Opus 51,381 words
The 3 Weakest Claims "94% accuracy decoding neural patterns into text… works with any language, any device" (Slide 3) Why it's weak: the claim implies parity with surgically implanted electrodes. The number to compare against is Willett et al.
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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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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…

Claude Opus 51,817 words
INVESTMENT COMMITTEE MEMO — LedgerLift Inc. (NASDAQ: LLLT) Analyst: [—] Date: [—] Price: $46.00 Mkt cap: $8.74B Net cash: $1.4B EV: $7.34B Fictional exercise. Not investment advice. Recommendation PASS on the long. Add to short bench (initiate 1.0–1.5% NAV on triggers below).
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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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Our Verdict
Claude Opus 5
Claude Opus 5
GPT-6 Luna
GPT-6 Luna

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

GPT-6 Luna costs 50x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Opus 5
Input
$5.00
Output
$25.00
GPT-6 Luna
Input
$0.10
50× cheaper
Output
$0.50
50× cheaper

GPT-6 Luna is cheaper on both: 50× input, 50× output.

Where to run it

7 hosts, cheapest first

Claude Opus 54 hosts
HostInOutContextUptime
Amazon Bedrock$5.00 in·$25.00 out·1M·99.7% upAzure AI Foundry$5.00 in·$25.00 out·1M·99.9% upAnthropic$5.00 in·$25.00 out·1M·99.9% upGoogle Vertex AI$5.00 in·$25.00 out·1M·99.8% 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

Claude Opus 5 is developed by Anthropic while GPT-6 Luna is developed by OpenAI. Claude Opus 5 has a 1.0M token context window vs GPT-6 Luna's 1.1M. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 5 and GPT-6 Luna 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.

Claude Opus 5 costs $5/M input tokens and GPT-6 Luna costs $0.1/M input tokens. GPT-6 Luna is $4.90/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 Claude Opus 5 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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