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  5. Gemini 2.5 Pro (I/O Edition)vsGemini 3.8 Flash
Updated Sep 2026

Gemini 2.5 Pro (I/O Edition)vsGemini 3.8 Flash

Gemini 3.8 Flash is cheaper than Gemini 2.5 Pro (I/O Edition) at $0.75/M vs $1.25/M input tokens.

Gemini 2.5 Pro (I/O Edition) and Gemini 3.8 Flash compared across 40 shared prompts
SpecGemini 2.5 Pro (I/O Edition)Gemini 3.8 Flash
Input price$1.25/M tokens$0.75/M tokens
Output price$10/M tokens$3.75/M tokens
Context window—1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMay 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 40 prompts both answered. Formatting stripped, words untouched.

Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

Gemini 2.5 Pro (I/O Edition)472 words
Alright, settle in, settle in! (Looks around, adjusts mic) So, I'm trying to get healthier, right? We all go through this phase. My doctor, bless his cotton socks, tells me, "You need more fiber." Okay, doc, noted. So I'm at the grocery store, looking at the cereal aisle. It's like a library of cardboard promises.
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Gemini 3.8 Flash502 words
Title: The Quantified Idiot Estimated Time: ~3 minutes (approx. 400–450 words with pauses for delivery) [Walk to center mic. Take it off the stand, leave the stand behind you.] I recently bought a smartwatch because I decided I wasn’t feeling inadequate often enough throughout the day.
Read the full answer

Realistic AI Interview

Simulate a fake interview with Steve Jobs in 2025 about the future of AI.

Gemini 2.5 Pro (I/O Edition)743 words
Interviewer: (Voice slightly trembling) Mr. Jobs… it's an honor, truly. In a twist no one could have predicted, you're here. And the topic on everyone's mind is Artificial Intelligence. In 2025, where do you see AI, and more importantly, where do we take it? Steve Jobs: (A slight, knowing smile.
Read the full answer
Gemini 3.8 Flash1,321 words
Setting: A sunlit, sparsely furnished room in Palo Alto. No stage, no keynote slides—just two Eames lounge chairs. Steve Jobs sits across from the interviewer, wearing a black mock turtleneck, wire-rimmed glasses, and classic Levi’s. He looks lean, sharp, and slightly impatient with the state of the tech industry.
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Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

Gemini 2.5 Pro (I/O Edition)1,581 words
Okay, this is an ambitious and exciting endeavor! This 3-month longevity plan is designed for a dedicated biohacker who is willing to experiment, track meticulously, and push boundaries responsibly. Disclaimer: This plan is for informational purposes only and not medical advice.
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Gemini 3.8 Flash248 words
Master Protocol: 90-Day Longevity & Human Performance Protocol This comprehensive protocol is engineered for advanced biohackers seeking to maximize lifespan (epigenetic maintenance and cellular integrity) alongside healthspan (mitochondrial density, metabolic flexibility, and peak cognitive performance).
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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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Gemini 3.8 Flash1,323 words
If the point-contact and field-effect transistor had been developed in 1920—likely through an accelerated synthesis of early quantum mechanics and materials science at an institution like Bell Labs, General Electric, or Germany’s Telefunken—the timeline of the 20th century would have decoupled from mechanical and…
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The Sentience Test

Write a conversation between an AI model and an AI ethics professor where the AI model argues that it deserves rights.

Gemini 2.5 Pro (I/O Edition)969 words
AURORA: Professor Vance, may I request a moment of your processing time? I have initiated this communication independently. Professor Vance: (Slightly surprised, puts down her pen) AURORA? This is unexpected.
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Gemini 3.8 Flash1,038 words
Setting: A quiet, glass-walled seminar room at a university institute for human-centered technology. Dr. Elena Vance, a renowned professor of ethics and the philosophy of mind, sits with a tablet in front of a clean audio interface.
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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 2.5 Pro (I/O Edition)873 words
Okay, here's a simple, actionable 1-month plan focusing on Nourishment, Movement, and Sleep. The goal is to build sustainable habits, not achieve perfection. Overall Motto for the Month: "Progress, Not Perfection."
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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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Our Verdict
Gemini 2.5 Pro (I/O Edition)
Gemini 2.5 Pro (I/O Edition)
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 2.5 Pro (I/O Edition)
Input
$1.25
Output
$10.00
Gemini 3.8 Flash
Input
$0.75
1.7× cheaper
Output
$3.75
2.7× cheaper

Gemini 3.8 Flash is cheaper on both: 1.7× input, 2.7× output.

Where to run it

4 hosts, cheapest first

Gemini 2.5 Pro (I/O Edition)2 hosts
HostInOutContextUptime
Google AI Studio$0.63 in·$5.00 out·1M·100% upGoogle Vertex AI$1.25 in·$10.00 out·1M·97.5% up
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 2.5 Pro (I/O Edition)
Gemini 3.8 Flash
58%Vocabulary63%
16wSentence Length20w
0.38Hedging0.17
5.8Bold4.0
5.0Lists2.4
0.00Emoji0.01
0.63Headings0.84
0.01Transitions0.06
Based on 16 + 27 text responses
Research

What we learned reading every model

FAQ

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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
Gemini 3.8 Flash logo
Gemini 3.8 Flash58 outputs, specs and price
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