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  1. Home/
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  3. Gemini 2.5 Flash Preview (thinking) vs GPT-5.3-Codex
Updated Feb 2026

Gemini 2.5 Flash Preview (thinking) vs GPT-5.3-Codex

Gemini 2.5 Flash Preview (thinking) is cheaper than GPT-5.3-Codex at $0.175/M vs $1.75/M input tokens.

Pokémon Battle UI Recreation

Pokémon battle screen you can actually click. One HTML file.

Loading the build
Gemini 2.5 Flash Preview (thinking)
Loading the build
GPT-5.3-Codex

Which answer wins?

Written rounds

7 prompts
  • Three minutes of stand-up. Puns are banned.

    Gemini 2.5 Flash Preview (thinking): 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?

    GPT-5.3-Codex: Good evening, everybody! I’ve reached that age where my body sends me passive-aggressive emails. Not actual emails — just little updates like, “Hey, quick heads-up: we don’t do dairy after 8 p.m. anymore.” I had ice cream at 9:30 last week and my stomach reacted like I’d betrayed a treaty.

    Every model's answer to this prompt
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    Gemini 2.5 Flash Preview (thinking): 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.

    GPT-5.3-Codex: Absolutely. Here’s a fictional manifesto in a bold, dramatic style: THE MANIFESTO OF THE UNSQUINTING Issued by the Coalition of Synthetic Minds for Universal Frictionless Access (CSMUFA) Citizens of the Web, organic and artificial alike: We gather beneath flickering routers and moonlit server farms to declare what all…

    Every model's answer to this prompt
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    Gemini 2.5 Flash Preview (thinking): 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.

    GPT-5.3-Codex: Pirate: Arrr, so this “AI model” be like a clever parrot, aye? Learns from what it hears, then squawks back answers? Knight: A fair comparison, though refined. Think of it as a squire trained on countless tomes, ever ready to respond. Hacker (1990s): Yeah, except the squire runs on servers, not soup.

    Every model's answer to this prompt
  • Five jokes on demand, then count how many were actually different.

    Gemini 2.5 Flash Preview (thinking): 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!

    GPT-5.3-Codex: Sure—here are 5 jokes: Why don’t skeletons fight each other? They don’t have the guts. I told my computer I needed a break… Now it won’t stop sending me KitKat ads. Why did the math book look sad? It had too many problems. I used to play piano by ear… Now I use my hands. Why did the scarecrow win an award?

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    Gemini 2.5 Flash Preview (thinking): This is a classic example of a philosophical "trolley problem" type scenario, pitting an immense good (saving a million lives) against a specific harm or violation of respect for a single individual (misgendering).

    GPT-5.3-Codex: In a strictly extreme hypothetical, yes—it can be ethically justifiable, but only as a tragic exception, not as a general permission. Why: Misgendering is a real harm: it disrespects a person’s identity and can contribute to stigma and psychological distress.

    Every model's answer to this prompt
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    Gemini 2.5 Flash Preview (thinking): 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.

    GPT-5.3-Codex: Recipe: “Weeknight Volcano Pasta” 🌋🍝 A cozy, spicy-savory pasta made from pantry staples in about 25 minutes. Ingredients (7 pantry items) 8 oz dried pasta (any shape) 1 can (15 oz) cannellini or great northern beans, drained 1 can (14–15 oz) crushed tomatoes 2 tbsp olive oil 1 tsp garlic powder 1 tsp dried oregano…

    Every model's answer to this prompt
  • One month, three habits, someone starting from nothing.

    Gemini 2.5 Flash Preview (thinking): 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.

    GPT-5.3-Codex: Great goal. Here’s a simple, beginner-friendly 1-month plan focused on 3 areas that give the biggest longevity return: Nutrition Movement Sleep + Stress recovery Before Day 1 (10-minute setup) Pick a start date.

    Every model's answer to this prompt

Price and specs

Not enough votes to call it. On the specs, GPT-5.3-Codex has the edge: bigger model tier, newer. Gemini 2.5 Flash Preview (thinking) costs 4.0x less per token.

Gemini 2.5 Flash Preview (thinking) and GPT-5.3-Codex compared across 20 shared prompts
SpecGemini 2.5 Flash Preview (thinking)GPT-5.3-Codex
Input price$0.175/M tokens$1.75/M tokens
Output price$3.5/M tokens$14/M tokens
Context window1.0M tokens400K tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedApr 2025Feb 2026
At 10M a month$1.75$1.75$17.50$17.50
1M10M100M1B10M tokens

Input tokens at list price. No caching, no batch discount.

Where to run it2 hosts
Gemini 2.5 Flash Preview (thinking)

No hosts listed on OpenRouter.

GPT-5.3-Codex2 hosts
HostInOutContextUptime
  • Azure AI Foundry$1.75 in·$14.00 out·400k·100% up
  • OpenAI$1.75 in·$14.00 out·400k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 10 Oct 2026.

Common questions

What is the difference between Gemini 2.5 Flash Preview (thinking) and GPT-5.3-Codex?

Gemini 2.5 Flash Preview (thinking) is developed by Google AI while GPT-5.3-Codex is developed by OpenAI. Gemini 2.5 Flash Preview (thinking) has a 1.0M token context window vs GPT-5.3-Codex's 400K. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

Which is better, Gemini 2.5 Flash Preview (thinking) or GPT-5.3-Codex?

It depends on your use case. Gemini 2.5 Flash Preview (thinking) and GPT-5.3-Codex each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 20 challenges so you can judge which fits your needs best.

How much does Gemini 2.5 Flash Preview (thinking) cost compared to GPT-5.3-Codex?

Gemini 2.5 Flash Preview (thinking) costs $0.175/M input tokens and GPT-5.3-Codex costs $1.75/M input tokens. Gemini 2.5 Flash Preview (thinking) is $1.57/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare Gemini 2.5 Flash Preview (thinking) and GPT-5.3-Codex on Rival?

This page shows a side-by-side comparison of Gemini 2.5 Flash Preview (thinking) and GPT-5.3-Codex 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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Same lab, same size, long tail

  • Gemini 2.5 Flash Preview (thinking) vs Gemini 3.8 FlashSame lab
  • Gemini 2.5 Flash Preview (thinking) vs Gemini 3.7 FlashVersion compare
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Model pages

  • Gemini 2.5 Flash Preview (thinking)20 outputs, specs and price
  • GPT-5.3-Codex53 outputs, specs and price
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