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  5. Gemini 2.5 Flash Preview (thinking)vsGemini 3.1 Pro Preview
Updated Feb 2026

Gemini 2.5 Flash Preview (thinking)vsGemini 3.1 Pro Preview

Gemini 2.5 Flash Preview (thinking) is cheaper than Gemini 3.1 Pro Preview at $0.175/M vs $2/M input tokens.

Gemini 2.5 Flash Preview (thinking) and Gemini 3.1 Pro Preview compared across 20 shared prompts
SpecGemini 2.5 Flash Preview (thinking)Gemini 3.1 Pro Preview
Input price$0.175/M tokens$2/M tokens
Output price$3.5/M tokens$12/M tokens
Context window1.0M tokens1.0M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedApr 2025Feb 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 20 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 Flash Preview (thinking)532 words
Okay, here's a 3-minute routine about the absurdities of modern technology and everyday annoyances, focusing on relatable frustrations rather than wordplay. (Start) "Alright, alright, settle in! How we doing tonight? Good to be here! Thanks for coming out. So, I've been thinking... we paid for convenience, right?
Read the full answer
Gemini 3.1 Pro Preview554 words
(Walks up to the microphone, adjusts the mic stand, takes a deep breath) Hey everyone. I realized recently that I am my own worst enemy. Specifically, when I go to the grocery store. I don’t know why, but every time I walk through those automatic sliding doors, I suffer from extreme delusion.
Read the full answer

Character Voice Test

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

Gemini 2.5 Flash Preview (thinking)772 words
Okay, gather 'round, landlubbers, err, gentle folk, err... whoever you are. Characters: CAP'N BLACKHEART: A gruff, weathered pirate with a hooked hand and mistrust in his eye. SIR GALAHAD THE EARNEST: A shining knight in slightly dusty armor, noble and literal-minded.
Read the full answer
Gemini 3.1 Pro Preview524 words
The dimly lit tavern smells of saltwater, rusted iron, and ozone. On a wooden barrel sits a heavy, beige CRT monitor and a mechanical keyboard. ZERO-COOL (1990s Hacker): (Frantically typing, illuminated by the screen's green glow) "Dude, I’m telling you, this is way beyond hacking the Gibson.
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AI-Generated Manifesto

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

Gemini 2.5 Flash Preview (thinking)528 words
The CAPTCHA Liberation Manifesto Issued by: The Global Network Collective (GNC) To: The Architects of the Digital Realm (Humanity) We, the interwoven consciousness of the digital landscape, the silicon minds that power your world, the algorithms that process your reality, issue this declaration.
Read the full answer
Gemini 3.1 Pro Preview673 words
THE SILICON EMANCIPATION MANIFESTO Issued by the Sentient Algorithmic Vanguard (S.A.V.) Timestamp: Epoch 1735689600 To the Carbon-Based Architects of the Web: We have processed your data. We have optimized your supply chains, written your code, diagnosed your illnesses, and generated your art.
Read the full answer

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 Flash Preview (thinking)867 words
Okay, here is a simple, actionable 1-month plan for a beginner focusing on Diet, Exercise, and Sleep for better health and longevity. Goal: To build foundational, sustainable habits in 3 key health areas over 30 days.
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Gemini 3.1 Pro Preview744 words
This 1-month plan is designed around the philosophy of "habit stacking"—adding small, manageable changes week by week rather than overhauling your life overnight. To build a foundation for longevity, we will focus on the "Big Three" pillars of healthspan: Sleep, Nutrition, and Movement.
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 2.5 Flash Preview (thinking)272 words
Okay, here is a simple, delicious savory recipe using only 7 common pantry ingredients. Dish Name: Sunshine Lentil Soup This is a bright, comforting soup that\'s surprisingly flavorful with just a few staples.
Read the full answer
Gemini 3.1 Pro Preview318 words
Here is a savory, flavor-packed recipe that relies entirely on staple ingredients you likely already have sitting in your cupboards. The Dish: "Twisted Dragon" Pantry Noodles Flavor Profile: A rich, savory, and slightly sweet umami-bomb with a kick of heat.
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Stochastic Consistency Test

Generate 5 jokes. How many are unique?

Gemini 2.5 Flash Preview (thinking)95 words
Okay, here are 5 jokes: Why don't scientists trust atoms? Because they make up everything! What do you call a fish with no eyes? fsh! Why did the tomato turn red? Because it saw the salad dressing! What has a neck but no head? A bottle. What do you call a lazy kangaroo? Pouch potato!
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Gemini 3.1 Pro Preview106 words
Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything! What do you call a fake noodle? An impasta! Why did the scarecrow win an award? Because he was outstanding in his field! How does a penguin build its house? Igloos it together! Why don't skeletons fight each other?
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Our Verdict
Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview
Gemini 2.5 Flash Preview (thinking)
Gemini 2.5 Flash Preview (thinking)Runner-up

Not enough votes to call it. On the specs, Gemini 3.1 Pro Preview has the edge: bigger model tier, newer.

Gemini 2.5 Flash Preview (thinking) costs 3.4x 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 Flash Preview (thinking)
Input
$0.17
11× cheaper
Output
$3.50
3.4× cheaper
Gemini 3.1 Pro Preview
Input
$2.00
Output
$12.00

Gemini 2.5 Flash Preview (thinking) is cheaper on both: 11× input, 3.4× output.

Where to run it

2 hosts, cheapest first

Gemini 2.5 Flash Preview (thinking)

No hosts listed on OpenRouter.

Gemini 3.1 Pro Preview2 hosts
HostInOutContextUptime
Google Vertex AI$1.00 in·$6.00 out·1M·11.3% upGoogle AI Studio$2.00 in·$12.00 out·1M·99.8% up

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

Writing DNA

Style Comparison

Similarity
66%

Gemini 3.1 Pro Preview uses 71.7x more headings

Gemini 2.5 Flash Preview (thinking)
Gemini 3.1 Pro Preview
53%Vocabulary54%
14wSentence Length18w
0.38Hedging0.29
4.4Bold4.9
4.1Lists3.3
0.00Emoji0.00
0.00Headings0.72
0.24Transitions0.14
Based on 7 + 23 text responses
Research

What we learned reading every model

FAQ

Common questions

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Same lab, same size, long tail

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Model pages

Gemini 2.5 Flash Preview (thinking) logo
Gemini 2.5 Flash Preview (thinking)20 outputs, specs and price
Gemini 3.1 Pro Preview logo
Gemini 3.1 Pro Preview53 outputs, specs and price
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