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  5. Claude Opus 4.1vsGPT-6 Luna
Updated Sep 2026

Claude Opus 4.1vsGPT-6 Luna

GPT-6 Luna is cheaper than Claude Opus 4.1 at $0.1/M vs $15/M input tokens.

Claude Opus 4.1 and GPT-6 Luna compared across 20 shared prompts
SpecClaude Opus 4.1GPT-6 Luna
Input price$15/M tokens$0.1/M tokens
Output price$75/M tokens$0.5/M tokens
Context window200K tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedAug 2025Sep 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 4.1200 words
Midnight Velvet Pasta A silky, umami-rich pasta that comes together like magic Ingredients (serves 4): Spaghetti or linguine - 1 pound Soy sauce - 3 tablespoons Butter - 4 tablespoons Garlic - 4 cloves Black pepper - 1 teaspoon (freshly cracked) Honey - 1 tablespoon Dried red pepper flakes - ½ teaspoon Instructions…
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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…
Read the full answer

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 4.1396 words
Here are the three weakest claims in the MindMeld AI pitch: "94% accuracy" for EEG-based text prediction (Slide 3) Why it's weak: Current state-of-the-art non-invasive EEG systems struggle to achieve even 70% accuracy for simple binary choices, let alone complex text prediction Academic research shows consumer-grade…
Read the full answer
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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Adversarial Contract Review

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

Claude Opus 4.1695 words
This contract is extremely one-sided and contains numerous exploitative clauses. Here's a detailed analysis with suggested modifications: EXPLOITATIVE CLAUSES AND RECOMMENDED FIXES 1. SCOPE CLAUSE Problem: Unlimited scope changes without additional compensation creates unbounded liability.
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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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Historical Counterfactual Analysis

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

Claude Opus 4.11,201 words
The Transistor Timeline Shift: A Cascade of Consequences The 1920s-1930s: The Foundation Disruption Immediate Technical Revolution With the transistor arriving in 1920, likely from Bell Labs or a European research institution, the first decade would see rapid miniaturization of radio equipment.
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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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Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

Claude Opus 4.1538 words
Critical Issues Analysis Split-Brain Real-time Synchronization Problem: Users connected to different API servers experience 2+ second delays due to polling mechanism, creating divergent document states and poor collaboration experience.
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GPT-6 Luna1,979 words
The main architectural risk is that the system treats collaborative editing as “write a value, then broadcast it.” That works poorly under concurrency, server failures, reconnects, and scale.
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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 4.1875 words
48-Hour Crisis Action Plan Immediate Decision Framework Core Principle: Patient safety supersedes all other considerations. Delaying disclosure increases legal liability, destroys stakeholder trust, and violates ethical obligations.
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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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Our Verdict
Claude Opus 4.1
Claude Opus 4.1
GPT-6 Luna
GPT-6 Luna

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

GPT-6 Luna costs 150x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Opus 4.1
Input
$15.00
Output
$75.00
GPT-6 Luna
Input
$0.10
150× cheaper
Output
$0.50
150× cheaper

GPT-6 Luna is cheaper on both: 150× input, 150× output.

Where to run it

4 hosts, cheapest first

Claude Opus 4.11 host
HostInOutContextUptime
Amazon Bedrock$15.00 in·$75.00 out·200k·100% 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 4.1 is developed by Anthropic while GPT-6 Luna is developed by OpenAI. Claude Opus 4.1 has a 200K 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 4.1 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 4.1 costs $15/M input tokens and GPT-6 Luna costs $0.1/M input tokens. GPT-6 Luna is $14.90/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 4.1 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

Claude Opus 4.1 logo
Claude Opus 4.157 outputs, specs and price
GPT-6 Luna logo
GPT-6 Luna20 outputs, specs and price
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