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  5. Gemini 3 Flash PreviewvsGPT-6 Luna Pro
Updated Sep 2026

Gemini 3 Flash PreviewvsGPT-6 Luna Pro

GPT-6 Luna Pro is cheaper than Gemini 3 Flash Preview at $0.1/M vs $0.5/M input tokens.

Gemini 3 Flash Preview and GPT-6 Luna Pro compared across 20 shared prompts
SpecGemini 3 Flash PreviewGPT-6 Luna Pro
Input price$0.5/M tokens$0.1/M tokens
Output price$3/M tokens$0.5/M tokens
Context window1.0M tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedDec 2025Sep 2026
Side by side

Same prompt, both answers

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

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…

Gemini 3 Flash Preview481 words
This 1-month plan is designed to build a foundation for longevity without causing burnout. We will focus on Nutrition, Movement, and Sleep. The goal for Month 1 isn't perfection; it’s consistency. Area 1: Nutrition (The "Crowding Out" Method) Instead of cutting everything out, focus on adding longevity-boosting foods.
Read the full answer
GPT-6 Luna Pro327 words
A simple 1-month plan for better health and longevity Choose three foundations: eating well, moving regularly, and sleeping consistently. Aim for steady habits, not perfection. Diet: Make nourishing choices easier Week 1: Add one serving of fruit or vegetables to one meal each day.
Read the full answer

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…

Gemini 3 Flash Preview691 words
Dish Title: "The Umami Forest" Concept: A conceptual exploration of the intersection between Earth and Sea. This dish pairs the earthy, bitter profile of Roasted White Chocolate with the saline, mineral intensity of Dried Sea Urchin (Uni) and Fermented Black Garlic.
Read the full answer
GPT-6 Luna Pro1,215 words
Turbot, Sea Buckthorn, Mussel Beurre Blanc, and Celery-Root Silk Serves 4 A composed main course built around an unusual but harmonious pairing: briny mussel and turbot with intensely tart, apricot-like sea buckthorn.
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.…

Gemini 3 Flash Preview550 words
This pitch for MindMeld AI contains several "red flags" that sophisticated investors would immediately challenge. Here are the three weakest claims, the reasoning behind their weakness, and how to fix them. The Technology Claim: "94% accuracy in decoding neural patterns into text."
Read the full answer
GPT-6 Luna Pro401 words
“94% accuracy” and “works with any language, any device” Why it’s weak: “Accuracy” is undefined. It could mean classifying a small set of prompted words in a controlled lab—not reliably generating free-form text.
Read the full answer

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 3 Flash Preview738 words
To: Investment Committee From: Equity Research Team Date: October 26, 2023 Subject: Investment Recommendation: LedgerLift (LLLT) 1. Recommendation: LONG 12-Month Price Target Range: $58 – $76 (Base to Bull Case) Thesis: LedgerLift is a high-quality mid-market SaaS compounder with exceptional unit economics (123% NRR)…
Read the full answer
GPT-6 Luna Pro888 words
LedgerLift (LLLT) — Investment Committee Memo Recommendation: Pass 12-month price target range: $28–44 per share LedgerLift has attractive customer economics, recurring revenue, and a credible path to margin expansion, but those strengths are already reflected in a $46 share price.
Read the full answer

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 3 Flash Preview344 words
This savory, comforting dish turns humble pantry staples into a high-end-tasting meal. The soy sauce and honey create a "sticky-sweet" glaze for the chickpeas, while the red pepper adds a gentle warmth.
Read the full answer
GPT-6 Luna Pro127 words
Golden Pantry Pancakes Fluffy, lightly sweet pancakes made with everyday staples. Makes: About 6 small pancakes Prep time: 5 minutes Cook time: 10 minutes Ingredients 1 cup all-purpose flour 1 cup milk 1 egg 2 tablespoons sugar 1 teaspoon baking powder ¼ teaspoon salt 2 tablespoons butter, melted (plus a little for the…
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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 3 Flash Preview756 words
If the transistor had been invented in 1920—likely via a breakthrough in vacuum tube research at Bell Labs or by a lone genius like Julius Lilienfeld—the 27-year acceleration would not just move dates forward; it would fundamentally alter the physical and political landscape of the 20th century.
Read the full answer
GPT-6 Luna Pro1,661 words
The biggest change would not be that 1920 suddenly gets modern computers. It would be that governments and firms have six or seven extra decades to develop semiconductor materials, manufacturing, and applications.
Read the full answer
Our Verdict
Gemini 3 Flash Preview
Gemini 3 Flash Preview
GPT-6 Luna Pro
GPT-6 Luna Pro

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

GPT-6 Luna Pro costs 6.0x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Gemini 3 Flash Preview
Input
$0.50
Output
$3.00
GPT-6 Luna Pro
Input
$0.10
5.0× cheaper
Output
$0.50
6.0× cheaper

GPT-6 Luna Pro is cheaper on both: 5.0× input, 6.0× output.

Where to run it

4 hosts, cheapest first

Gemini 3 Flash Preview2 hosts
HostInOutContextUptime
Google Vertex AI$0.25 in·$1.50 out·1M·96.6% upGoogle AI Studio$0.50 in·$3.00 out·1M·99.9% up
GPT-6 Luna Pro2 hosts
HostInOutContextUptime
Azure AI Foundry$0.10 in·$0.50 out·1.1M·98.6% upOpenAI$0.10 in·$0.50 out·1.1M·99.9% up

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

Research

What we learned reading every model

FAQ

Common questions

Gemini 3 Flash Preview is developed by Google AI while GPT-6 Luna Pro is developed by OpenAI. Gemini 3 Flash Preview has a 1.0M token context window vs GPT-6 Luna Pro'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. Gemini 3 Flash Preview and GPT-6 Luna Pro 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 3 Flash Preview costs $0.5/M input tokens and GPT-6 Luna Pro costs $0.1/M input tokens. GPT-6 Luna Pro is $0.40/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 3 Flash Preview and GPT-6 Luna Pro 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

Gemini 3 Flash Preview logo
Gemini 3 Flash Preview59 outputs, specs and price
GPT-6 Luna Pro logo
GPT-6 Luna Pro20 outputs, specs and price
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