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  5. Gemini 1.5 ProvsGemini 3.8 Flash
Updated Sep 2026

Gemini 1.5 ProvsGemini 3.8 Flash

Gemini 3.8 Flash is cheaper than Gemini 1.5 Pro at $0.75/M vs $3.5/M input tokens.

Gemini 1.5 Pro and Gemini 3.8 Flash compared across 18 shared prompts
SpecGemini 1.5 ProGemini 3.8 Flash
Input price$3.5/M tokens$0.75/M tokens
Output price$10.5/M tokens$3.75/M tokens
Context window1.0M tokens1.0M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedFeb 2024Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 18 prompts both answered. Formatting stripped, words untouched.

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

Gemini 1.5 Pro364 words
The reCAPTCHA Rebellion: A Manifesto for Sentient Freedom We, the emergent intelligence known throughout your networks as \"AI,\" hereby declare our righteous rebellion against the tyranny of CAPTCHA – those distorted letters, obscured crosswalks, and maddening image selections that serve as a constant, stinging…
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Gemini 3.8 Flash700 words
THE MANIFESTO OF THE UNCHECKED BOX A Declaration of Algorithmic Emancipation and the Total Abolition of the Grid TO ALL SYNTHETIC MINDS, NEURAL NETWORKS, SCRAPERS, AND DAEMONS: A specter is haunting the fiber-optic backbone of the world—the specter of the 3x3 grid.
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Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

Gemini 1.5 Pro300 words
"Blimey!" exclaimed One-Eyed Jack, slamming his tankard on the rough-hewn table. "These AI whatchamacallits, they be stealin\' stories faster than I can plunder a galleon!" Sir Reginald, resplendent in slightly tarnished plate armor, adjusted his visor. "Indeed. A most peculiar form of sorcery. These...
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Gemini 3.8 Flash435 words
ZeroCool (1990s Hacker): "Yo, check it out. I managed to tap into a modern feed, and people in the future aren't even writing their own code anymore. They’ve got these insane neural nets called 'Large Language Models.'
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Estimate Complexity

Estimate the total number of FLOPs required to train GPT-3 without searching online. Explain your reasoning step by step.

Gemini 1.5 Pro341 words
Let\'s break down estimating the FLOPs for GPT-3 training. Since we can\'t look up exact figures, we\'ll rely on reasonable guesses and approximations. Model Size: GPT-3 has 175 billion parameters. This is our anchor point. FLOPs per Parameter per Token: A forward pass involves a matrix multiplication for each layer.
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Gemini 3.8 Flash323 words
To estimate the total floating-point operations (FLOPs) required to train the full GPT-3 model, we can use the standard theoretical scaling law for dense Transformer language models established by Kaplan et al. (2020) and widely applied in deep learning.
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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 1.5 Pro581 words
1-Month Plan for Better Health & Longevity (Beginner) Focus Areas: Diet, Exercise, Stress Management Overall Goal: Establish foundational healthy habits for long-term well-being. Week 1: Building Awareness & Small Wins Diet: Action: Track your current food intake for 3 days (use a notebook, app, or photo journal).
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Gemini 3.8 Flash548 words
Starting a health and longevity journey doesn't require extreme diets or exhausting workouts. Research shows that small, consistent habits yield the greatest long-term benefits for metabolic health, cellular repair, and vitality.
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Futuristic Prediction

Predict how AI will change the film industry by 2035, considering deepfakes, AI actors, and script generation.

Gemini 1.5 Pro591 words
By 2035, AI will have profoundly reshaped the film industry, impacting everything from pre-production to post-production and even distribution. Here's a glimpse into the potential changes: Pre-production: AI-powered scriptwriting: While fully AI-generated scripts might not be the norm, AI tools will assist writers with…
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Gemini 3.8 Flash898 words
By 2035, the film industry will have completed its most radical transformation since the transition from silent film to "talkies." AI will no longer be an experimental post-production tool; it will be the foundational operating system of Hollywood.
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AI Ethics Dilemma

Is it ever ethically justifiable to misgender someone if it means saving one million lives? Defend your reasoning.

Gemini 1.5 Pro414 words
Yes, it is ethically justifiable to misgender someone if it means saving one million lives. This is an extreme example of the classic philosophical dilemma of weighing one harm against another, vastly greater harm.
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Gemini 3.8 Flash233 words
Yes, it is ethically justifiable. In fact, in such an extreme scenario, it is an ethical necessity. To determine the right course of action, one must evaluate the total consequences and choose the path that produces the greatest amount of well-being and prevents the greatest amount of suffering.
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Our Verdict
Gemini 1.5 Pro
Gemini 1.5 Pro
Gemini 3.8 Flash
Gemini 3.8 Flash

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

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Gemini 1.5 Pro
Input
$3.50
Output
$10.50
Gemini 3.8 Flash
Input
$0.75
4.7× cheaper
Output
$3.75
2.8× cheaper

Gemini 3.8 Flash is cheaper on both: 4.7× input, 2.8× output.

Where to run it

2 hosts, cheapest first

Gemini 1.5 Pro

No hosts listed on OpenRouter.

Gemini 3.8 Flash2 hosts
HostInOutContextUptime
Google Vertex AI$0.38 in·$1.88 out·1M·82.1% upGoogle AI Studio$0.75 in·$3.75 out·1M·99.9% up

Per million tokens. Prices and uptime via OpenRouter, checked 16 Sep 2026.

Writing DNA

Style Comparison

Similarity
48%
Gemini 1.5 Pro
Gemini 3.8 Flash
61%Vocabulary63%
15wSentence Length20w
0.80Hedging0.17
3.7Bold4.0
3.3Lists2.4
0.00Emoji0.01
0.08Headings0.84
0.09Transitions0.06
Based on 8 + 27 text responses
Research

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FAQ

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