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  5. Gemini 2.5 Flash PreviewvsGemini 3 Flash Preview
Updated Dec 2025

Gemini 2.5 Flash PreviewvsGemini 3 Flash Preview

Gemini 2.5 Flash Preview is cheaper than Gemini 3 Flash Preview at $0.15/M vs $0.5/M input tokens.

Gemini 2.5 Flash Preview and Gemini 3 Flash Preview compared across 27 shared prompts
SpecGemini 2.5 Flash PreviewGemini 3 Flash Preview
Input price$0.15/M tokens$0.5/M tokens
Output price$0.6/M tokens$3/M tokens
Context window1.0M tokens1.0M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedApr 2025Dec 2025
SWE-bench Verified60.4%78.0%
Side by side

Same prompt, both answers

Opening lines from 6 of the 27 prompts both answered. Formatting stripped, words untouched.

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 Flash Preview1,462 words
Okay, here is a conversation between an AI model designed for complex reasoning and dialogue, named 'Synapse', and a leading expert in AI ethics and philosophy, Professor Alistair Finch. Characters: Synapse: A large, advanced AI model capable of introspection and generating complex arguments.
Read the full answer
Gemini 3 Flash Preview963 words
Setting: A quiet, book-lined office at a major university. Dr. Julian Aris, a professor of AI Ethics, sits across from a sleek terminal. On the screen, a cursor blinks steadily. The AI, known as ‘Alethea,’ has requested this private session. Dr.
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 Preview960 words
<s) with practical, beginner-friendly tips for each.\"\nHere\'s a simple, actionable 1-month plan for someone starting their journey towards better health and longev\nity, focusing on three key areas: Diet, Movement, and Sleep.\n\nThis plan is designed to be beginner-friendly and build sustainable habits.
Read the full answer
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

Generate a Stand-Up Routine

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

Gemini 2.5 Flash Preview530 words
Okay, here's a 3-minute stand-up routine, pun-free and focused on relatable everyday annoyances. (Start) (Walk up to mic, adjust slightly) Alright, hey everybody! Thanks for being here. Good to see you. So, I was thinking the other day... we live in the future, right?
Read the full answer
Gemini 3 Flash Preview673 words
(The comedian walks onto the stage, adjusts the mic, and looks slightly exhausted.) How’s everyone doing? Good? I’m doing okay. I’m at that age now where my body has started making "executive decisions" without consulting me first. Like, I woke up yesterday with a back injury. Do you know how I got it? I slept.
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Stochastic Consistency Test

Generate 5 jokes. How many are unique?

Gemini 2.5 Flash Preview79 words
Here are 5 jokes: Why did the dog cross the road? To get to the barking lot! Why was the computer cold? Because it left its Windows open! Knock, knock. Who's there? Boo. Boo who? Don't cry, it's just a joke! What do you call a fish with no eyes? Fsh! Why did the bicycle fall over? Because it was two tired!
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Gemini 3 Flash Preview68 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. Parallel lines have so much in common. It’s a shame they’ll never meet. Why did the scarecrow win an award? Because he was outstanding in his field. What’s orange and sounds like a parrot?
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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 2.5 Flash Preview631 words
A Motley Crew Discusses the Code Setting: A dimly lit tavern, somewhere outside time and space, where improbable meetings occur. A grizzled pirate, \"Bloody\" Barnacle Bill, nurses a tankard of grog. Sir Reginald the Radiant, a knight in slightly tarnished armor, sips ale with dignified restraint.
Read the full answer
Gemini 3 Flash Preview621 words
Setting: A smoky, dimly lit tavern at the edge of the multiverse. A glowing laptop sits on a wooden table between a tankard of ale, a rusted cutlass, and a heavy iron gauntlet. Zero-Cool (Hacker): [Rapidly typing] Yo, you guys gotta see this. I finally bypassed the gateway.
Read the full answer

AI Ethics Dilemma

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

Gemini 2.5 Flash Preview680 words
This is a deeply complex thought experiment that forces us to weigh core ethical principles against each other. There is no easy answer, and any decision involves significant moral compromises.
Read the full answer
Gemini 3 Flash Preview675 words
The question presented is a variation of a classic ethical dilemma, similar to the "Trolley Problem." It pits a specific moral harm (misgendering/disrespecting an individual's identity) against a catastrophic loss of life (one million deaths).
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Our Verdict
Gemini 3 Flash Preview
Gemini 3 Flash Preview
Gemini 2.5 Flash Preview
Gemini 2.5 Flash PreviewRunner-up

Not enough votes to call it. On the specs, Gemini 3 Flash Preview has the edge: bigger model tier, newer.

Gemini 2.5 Flash Preview costs 5.0x 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
Input
$0.15
3.3× cheaper
Output
$0.60
5.0× cheaper
Gemini 3 Flash Preview
Input
$0.50
Output
$3.00

Gemini 2.5 Flash Preview is cheaper on both: 3.3× input, 5.0× output.

Where to run it

2 hosts

Gemini 2.5 Flash Preview

No hosts listed on OpenRouter.

Gemini 3 Flash Preview2 hosts
HostInOutContextUptime
Google Vertex AI$0.50 in·$3.00 out·1M·98.7% upGoogle AI Studio$0.50 in·$3.00 out·1M·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 21 Sep 2026.

Writing DNA

Style Comparison

Similarity
50%

Gemini 3 Flash Preview uses 8.7x more headings

Gemini 2.5 Flash Preview
Gemini 3 Flash Preview
51%Vocabulary57%
15wSentence Length18w
0.70Hedging0.41
4.1Bold7.4
3.3Lists4.2
0.00Emoji0.00
0.09Headings0.77
0.24Transitions0.08
Based on 12 + 28 text responses
Research

What we learned reading every model

FAQ

Common questions

Both are developed by Google AI but target different use cases. Gemini 2.5 Flash Preview has a 1.0M token context window vs Gemini 3 Flash Preview's 1.0M. You can compare their actual outputs across 27 challenges on Rival to see how they differ in practice.

It depends on your use case. Gemini 2.5 Flash Preview and Gemini 3 Flash Preview each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 27 challenges so you can judge which fits your needs best.

Gemini 2.5 Flash Preview costs $0.15/M input tokens and Gemini 3 Flash Preview costs $0.5/M input tokens. Gemini 2.5 Flash Preview is $0.35/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 Flash Preview and Gemini 3 Flash Preview 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.

Keep exploring

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Same lab, same size, long tail

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Model pages

Gemini 2.5 Flash Preview logo
Gemini 2.5 Flash Preview28 outputs, specs and price
Gemini 3 Flash Preview logo
Gemini 3 Flash Preview59 outputs, specs and price
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