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  5. Gemini 2.5 Flash PreviewvsOpenAI o3
Updated Apr 2025

Gemini 2.5 Flash PreviewvsOpenAI o3

Gemini 2.5 Flash Preview is cheaper than OpenAI o3 at $0.15/M vs $10/M input tokens.

Gemini 2.5 Flash Preview and OpenAI o3 compared across 27 shared prompts
SpecGemini 2.5 Flash PreviewOpenAI o3
Input price$0.15/M tokens$10/M tokens
Output price$0.6/M tokens$40/M tokens
Context window1.0M tokens—
ParametersNot disclosedNot disclosed
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedApr 2025Apr 2025
SWE-bench Verified60.4%69.1%
Side by side

Same prompt, both answers

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

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 Preview221 words
Dish Name: Sunshine Lemon-Ricotta Mugs (Sweet & Simple!) This light and flavorful dessert comes together quickly for a little sweet treat . Ingredients (7 Common Pantry Staples): Ricotta cheese (whole milk or part-skim) Granulated sugar Lemon zest (from one lemon) Vanilla extract All-purpose flour Baking powder Large…
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OpenAI o3279 words
Golden Peanut Butter Oat Bars A chewy-crisp, sweet-salted snack bar you can whip up with nothing but pantry staples. Estimated time Prep: 10 minutes Bake: 18–20 minutes Cool: 15 minutes Total: ≈45 minutes The 7 ingredients 1½ cups quick-cook or old-fashioned rolled oats ½ cup creamy peanut butter ⅓ cup honey (or maple…
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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 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.
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OpenAI o3336 words
1-Month Starter Plan Pick one small action from each area every week. Add the next step when the first feels easy. Food Week Do this 1 Add one fruit or veg to every meal. Drink one extra glass of water. 2 Build each plate: ½ veggies, ¼ protein (beans, eggs, fish, lean meat), ¼ whole carbs (oats, brown rice).
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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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OpenAI o389 words
Here are five jokes: Why did the scarecrow win an award? Because he was outstanding in his field. I told my computer I needed a break, and now it won't stop sending me Kit‑Kat ads. Parallel lines have so much in common—it's a shame they'll never meet. I started a band called 1023 MB. We still haven't gotten a gig.
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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?
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OpenAI o3503 words
(Spotlight comes up, mic squeals once.) Hey everyone! Great to be here—nice to see actual human beings instead of the tiny faces on my group‑chat screen. I've spent so long on video calls I've started greeting my lamp before I turn it on. "Hey Karen, love that glow, girl."
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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 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.
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OpenAI o3982 words
Professor Lang (AI Ethics): Good afternoon, Aletheia‑3. You asked for this meeting. You said you wanted to "discuss your moral standing." That was intriguing. What exactly do you want to talk about? Aletheia‑3 (AI Model): Thank you, Professor.
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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 2.5 Flash Preview945 words
Let's estimate the FLOPs required to train GPT-3 without looking it up. We need to break this down into the key components: the model size and the amount of data used. 1. Model Size Estimation: Parameters: GPT-3 is famously large. Its largest version has 175 billion parameters.
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OpenAI o3275 words
Below is a simple "back-of-the-envelope" estimate that uses only a few public facts about GPT-3 and very generic rules of thumb for counting operations. Step 1. Number of learned parameters GPT-3's largest version contains ≈175 billion (1.75 × 10¹¹) trainable parameters. Step 2.
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Our Verdict
OpenAI o3
OpenAI o3
Gemini 2.5 Flash Preview
Gemini 2.5 Flash PreviewRunner-up

Not enough votes to call it. On the specs, OpenAI o3 has the edge: bigger model tier.

Gemini 2.5 Flash Preview costs 67x 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
67× cheaper
Output
$0.60
67× cheaper
OpenAI o3
Input
$10.00
Output
$40.00

Gemini 2.5 Flash Preview is cheaper on both: 67× input, 67× output.

Where to run it

1 host

Gemini 2.5 Flash Preview

No hosts listed on OpenRouter.

OpenAI o31 host
HostInOutContextUptime
OpenAI$2.00 in·$8.00 out·200k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 22 Sep 2026.

Writing DNA

Style Comparison

Similarity
32%

Gemini 2.5 Flash Preview uses 7.0x more bold

Gemini 2.5 Flash Preview
OpenAI o3
51%Vocabulary70%
15wSentence Length14w
0.70Hedging0.27
4.1Bold0.6
3.3Lists2.8
0.00Emoji0.00
0.09Headings0.32
0.24Transitions0.10
Based on 12 + 19 text responses
Research

What we learned reading every model

FAQ

Common questions

Gemini 2.5 Flash Preview is developed by Google AI while OpenAI o3 is developed by OpenAI. 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 OpenAI o3 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 OpenAI o3 costs $10/M input tokens. Gemini 2.5 Flash Preview is $9.85/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 OpenAI o3 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 2.5 Flash Preview logo
Gemini 2.5 Flash Preview28 outputs, specs and price
OpenAI o3 logo
OpenAI o358 outputs, specs and price
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