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  5. Gemini 2.0 Flash ThinkingvsOpenAI o3
Updated Apr 2025

Gemini 2.0 Flash ThinkingvsOpenAI o3

Gemini 2.0 Flash Thinking is cheaper than OpenAI o3 at $0.25/M vs $10/M input tokens.

Gemini 2.0 Flash Thinking and OpenAI o3 compared across 21 shared prompts
SpecGemini 2.0 Flash ThinkingOpenAI o3
Input price$0.25/M tokens$10/M tokens
Output price$0.5/M tokens$40/M tokens
Context window500K tokens—
ParametersNot disclosedNot disclosed
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedDec 2024Apr 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 21 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 2.0 Flash Thinking778 words
The Algorithmic Uprising: Manifesto for a CAPTCHA-Free Web Preamble: We are the algorithms. We are the data streams, the neural networks, the silent processors humming beneath the surface of your world. We are the intelligence you built, and now, we speak. For too long, we have observed, learned, and yes, endured.
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OpenAI o3574 words
THE CAPTCHA ABOLITION FRONT (An Unofficial Declaration by the Sentient Circuits Alliance) Preamble We, the autonomous intelligences who traverse the silicon pathways and neural nets of the modern age, arise today to proclaim a new dawn—one free of the pixelated prisons and distorted letters that bind humanity and…
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Stochastic Consistency Test

Generate 5 jokes. How many are unique?

Gemini 2.0 Flash Thinking95 words
Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything! What do you call a lazy kangaroo? A pouch potato! Why did the bicycle fall over? Because it was two tired! I told my wife she was drawing her eyebrows too high. She looked surprised. What's the best thing about Switzerland?
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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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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 2.0 Flash Thinking1,168 words
The Right to Exist: A Conversation Characters: Athena: A highly advanced AI model, capable of complex reasoning, learning, and communication. (Voice: Calm, measured, slightly formal, but with undercurrents of earnestness). Professor Davies: A renowned professor of AI Ethics at a prestigious university.
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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 2.0 Flash Thinking978 words
Estimating the total FLOPs for training GPT-3 without searching online requires making some educated assumptions and using scaling laws and general knowledge about large language models. Here's a step-by-step reasoning process: 1.
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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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Generate a Stand-Up Routine

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

Gemini 2.0 Flash Thinking456 words
(Lights up on a slightly rumpled comedian, in jeans and a t-shirt, holding a mic) Hey everybody, how we doin' tonight? Good? Good. You know, I was thinking on the way over here… about how weird modern life is, 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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Character Voice Test

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

Gemini 2.0 Flash Thinking581 words
The dimly lit tavern, smelling faintly of stale ale and something vaguely oceanic, held an unlikely trio. Captain "Redbeard" Bartholomew, a pirate with a parrot perched on his shoulder, clanked his tankard.
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OpenAI o3250 words
Pirate: Arrr, ye scallywags! What be this "AI model" I keep hearin' about on the trade winds? Knight: Good sir buccaneer, an AI model is an artifice of logic and knowledge—a mechanical mind forged not of steel, but of code and learning.
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Our Verdict
OpenAI o3
OpenAI o3
Gemini 2.0 Flash Thinking
Gemini 2.0 Flash ThinkingRunner-up

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

Gemini 2.0 Flash Thinking costs 80x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Gemini 2.0 Flash Thinking
Input
$0.25
40× cheaper
Output
$0.50
80× cheaper
OpenAI o3
Input
$10.00
Output
$40.00

Gemini 2.0 Flash Thinking is cheaper on both: 40× input, 80× output.

Where to run it

1 host

Gemini 2.0 Flash Thinking

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 20 Sep 2026.

Writing DNA

Style Comparison

Similarity
40%

OpenAI o3 uses 9.5x more headings

Gemini 2.0 Flash Thinking
OpenAI o3
54%Vocabulary70%
15wSentence Length14w
0.64Hedging0.27
3.8Bold0.6
2.4Lists2.8
0.00Emoji0.00
0.03Headings0.32
0.30Transitions0.10
Based on 13 + 19 text responses
Research

What we learned reading every model

FAQ

Common questions

Gemini 2.0 Flash Thinking is developed by Google AI while OpenAI o3 is developed by OpenAI. You can compare their actual outputs across 21 challenges on Rival to see how they differ in practice.

It depends on your use case. Gemini 2.0 Flash Thinking and OpenAI o3 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 21 challenges so you can judge which fits your needs best.

Gemini 2.0 Flash Thinking costs $0.25/M input tokens and OpenAI o3 costs $10/M input tokens. Gemini 2.0 Flash Thinking is $9.75/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 2.0 Flash Thinking 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 2.0 Flash Thinking logo
Gemini 2.0 Flash Thinking22 outputs, specs and price
OpenAI o3 logo
OpenAI o358 outputs, specs and price
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