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  5. Gemini 2.5 Pro (I/O Edition)vsGPT-6 Luna
Updated Sep 2026

Gemini 2.5 Pro (I/O Edition)vsGPT-6 Luna

GPT-6 Luna is cheaper than Gemini 2.5 Pro (I/O Edition) at $0.1/M vs $1.25/M input tokens.

Gemini 2.5 Pro (I/O Edition) and GPT-6 Luna compared across 20 shared prompts
SpecGemini 2.5 Pro (I/O Edition)GPT-6 Luna
Input price$1.25/M tokens$0.1/M tokens
Output price$10/M tokens$0.5/M tokens
Context window—1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMay 2025Sep 2026
Side by side

Same prompt, both answers

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

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.…

Gemini 2.5 Pro (I/O Edition)883 words
Of course. This is a fascinating and ambitious pitch. Here are the 3 weakest claims, why they are weak, and how to strengthen them. Weak Claim #1: The Accuracy Claim The Claim (from Slide 3): "Our proprietary EEG headband... decode[s] neural patterns into text with 94% accuracy. Works with any language, any device."
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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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Historical Counterfactual Analysis

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

Gemini 2.5 Pro (I/O Edition)1,386 words
Excellent question. Let's trace the cascading effects of a 1920 transistor invention. This 27-year head start would fundamentally reshape the 20th century. The Foundation: 1920-1939 - The "Silicon Twenties" In our timeline (OTL), the 1920s and 30s were the age of the vacuum tube.
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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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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…

Gemini 2.5 Pro (I/O Edition)1,505 words
This is a company-defining crisis. My actions in the next 48 hours will determine not only the company's survival but also my own legacy and, most importantly, the well-being of 4 million patients. My guiding principle must be: Patient safety is not negotiable.
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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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Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

Gemini 2.5 Pro (I/O Edition)53 words
Here is the underwriting analysis for HarborTech Services (HTS). 1. Simplified LBO Model (FY2026–FY2030) First, the entry transaction is calculated to determine the initial equity investment.
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GPT-6 Luna405 words
All figures in $m. Assumptions: annual Term Loan amortization is 1% of original principal ($4.8m); cash interest is based on beginning-of-year balances; Mezz PIK compounds annually.
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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…

Gemini 2.5 Pro (I/O Edition)339 words
Okay, here\'s a simple and surprisingly delicious savory dish! "Sunshine Pantry Pilaf" This quick pilaf uses canned chickpeas for protein and texture, with a sunny, aromatic flavor from common pa\nntry spices.
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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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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…

Gemini 2.5 Pro (I/O Edition)73 words
INTERNAL INVESTMENT COMMITTEE MEMORANDUM TO: Investment Committee FROM: [Analyst Name] DATE: October 26, 2023 SUBJECT: Short Recommendation on LedgerLift (LLLT) Recommendation & Thesis Recommendation: SHORT 12-Month Price Target Range: $25.00 - $35.00 (24-46% Downside) Thesis: LedgerLift is a high-quality SaaS business…
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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
Gemini 2.5 Pro (I/O Edition)
Gemini 2.5 Pro (I/O Edition)
GPT-6 Luna
GPT-6 Luna

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

GPT-6 Luna costs 20x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Gemini 2.5 Pro (I/O Edition)
Input
$1.25
Output
$10.00
GPT-6 Luna
Input
$0.10
13× cheaper
Output
$0.50
20× cheaper

GPT-6 Luna is cheaper on both: 13× input, 20× output.

Where to run it

5 hosts, cheapest first

Gemini 2.5 Pro (I/O Edition)2 hosts
HostInOutContextUptime
Google Vertex AI$1.25 in·$10.00 out·1M·98.7% upGoogle AI Studio$1.25 in·$10.00 out·1M·98.9% 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

Gemini 2.5 Pro (I/O Edition) is developed by Google AI while GPT-6 Luna is developed by OpenAI. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

It depends on your use case. Gemini 2.5 Pro (I/O Edition) 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.

Gemini 2.5 Pro (I/O Edition) costs $1.25/M input tokens and GPT-6 Luna costs $0.1/M input tokens. GPT-6 Luna is $1.15/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 Gemini 2.5 Pro (I/O Edition) 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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Same lab, same size, long tail

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Model pages

Gemini 2.5 Pro (I/O Edition) logo
Gemini 2.5 Pro (I/O Edition)42 outputs, specs and price
GPT-6 Luna logo
GPT-6 Luna20 outputs, specs and price
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