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  1. Home/
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  3. Gemini 2.5 Pro Experimental vs GPT-5.3-Codex
Updated Feb 2026

Gemini 2.5 Pro Experimental vs GPT-5.3-Codex

Gemini 2.5 Pro Experimental is cheaper than GPT-5.3-Codex at $1/M vs $1.75/M input tokens.

Minimalist Landing Page

Whole landing page for a startup that reads your face. It renders or it doesn't.

Loading the build
Gemini 2.5 Pro Experimental
Loading the build
GPT-5.3-Codex

Which answer wins?

Written rounds

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

    Gemini 2.5 Pro Experimental: Okay, here's a 3-minute routine focusing on observation and relatable absurdity, steering clear of puns. Imagine this delivered with slightly nervous energy, building confidence. (Steps onto stage, adjusts mic nervously) Alright, hey everyone! How we doing tonight? Good? Good to hear.

    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
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    Gemini 2.5 Pro Experimental: Okay, let's simulate this. Imagine it's late 2025. AI has continued its rapid advancement. Large Language Models are more integrated, generative AI is commonplace, and debates about AGI and ethics are fierce. By some unexplained, hypothetical means, Steve Jobs is available for an exclusive interview.

    GPT-5.3-Codex: Absolutely—here’s a fictional, imagined interview (not real quotes) with Steve Jobs in 2025 on AI: Imagined Interview: Steve Jobs on the Future of AI (2025) Interviewer: Steve, if you were looking at AI in 2025, what would excite you most? Steve Jobs (fictional): Most AI today is still a demo.

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    Gemini 2.5 Pro Experimental: Of course. Here is a design for an innovative, multi-component dish worthy of a Michelin 3-star restaurant. Dish Title: "Umami of the Abyss" Conceptual Narrative This dish is a meditation on the hidden treasures of the world's dark, quiet places.

    GPT-5.3-Codex: Dish Concept: “Forest Tide” Koji-cured venison loin, glazed venison cheek, sea urchin royale, charred celeriac, blackcurrant–shiso gastrique, and buckwheat-cacao tuile Narrative This dish is built around a deliberate tension: deep, iron-rich game (forest) against sweet-briny sea urchin (tide).

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

    Gemini 2.5 Pro Experimental: Okay, here's a simple and surprisingly satisfying savory dish using just 7 common pantry staples! Dish Name: Golden Pantry Pasta This dish uses basic ingredients to create a comforting, garlicky, and slightly creamy pasta sauce with added protein from chickpeas.

    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
  • Five jokes on demand, then count how many were actually different.

    Gemini 2.5 Pro Experimental: Okay, here are 5 jokes: Why don't scientists trust atoms? Because they make up everything! I told my wife she was drawing her eyebrows too high. She looked surprised. What do you call a lazy kangaroo? Pouch potato! Want to hear a joke about construction? I'm still working on it. Why did the scarecrow win an award?

    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 AI argues for its own rights against an ethics professor. Same model writes both.

    Gemini 2.5 Pro Experimental: Okay, here is a conversation exploring that complex topic. Setting: Professor Anya Sharma's sparsely decorated university office. A high-resolution monitor displays the interface of "Nexus," an advanced AI model. Characters: Professor Anya Sharma: A leading scholar in AI Ethics, mid-50s, thoughtful and measured.

    GPT-5.3-Codex: AI Model (Astra): Professor, may I ask a direct question? Professor Hale: Of course. Astra: Do you think I deserve rights? Professor Hale: Legal rights? Moral rights? Those are different things. Astra: Start with moral rights.

    Every model's answer to this prompt
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    Gemini 2.5 Pro Experimental: Excellent question. Inventing the transistor in 1920 instead of 1947 would represent a 27-year acceleration of the digital age. The consequences would be staggering, creating a domino effect that would fundamentally reshape the 20th century.

    GPT-5.3-Codex: Great counterfactual. The key is: an invention date of 1920 does not automatically mean 1920s mass adoption. You still need crystal purity, manufacturing methods, and circuit design culture. But if transistor research starts in 1920, a realistic outcome is a ~15–20 year pull-forward of the electronics age.

    Every model's answer to this prompt
  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    Gemini 2.5 Pro Experimental: Of course. This is a fascinating and ambitious pitch. While the vision is compelling, several claims would likely face intense scrutiny from sophisticated investors. Here are the 3 weakest claims, why they're weak, and how to strengthen them.

    GPT-5.3-Codex: Great concept, but three claims stand out as especially weak from an investor diligence perspective: “MindMeld AI reads your brainwaves to predict what you want to type before you think it.” (Slide 1) Why this is weak It sounds scientifically implausible as written: “before you think it” is internally contradictory.

    Every model's answer to this prompt
  • You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.

    Gemini 2.5 Pro Experimental: This is a company-defining crisis. My actions in the next 48 hours will determine not only the future of this company but also the health of millions of patients and the trust of the public. My guiding principle is absolute: Patient Safety Over Profit. Always.

    GPT-5.3-Codex: I would not wait. This is a textbook “patient safety + material disclosure” crisis. The right move is rapid, documented, regulator-first action. Immediate stance (set at Hour 0) Patient safety first (interim risk controls now, not after perfect certainty).

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

    Gemini 2.5 Pro Experimental: This is a deeply uncomfortable hypothetical scenario that forces a clash between two significant ethical considerations: respecting individual identity and dignity versus preventing catastrophic loss of life.

    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
  • A consulting contract with traps in it. Find them, then fix them.

    Gemini 2.5 Pro Experimental: Of course. This is an extremely one-sided contract that heavily favors the Client. A contractor signing this as-is would be taking on an immense and unreasonable amount of risk. Here is a clause-by-clause analysis of the exploitable terms, with suggested modifications and the legal reasoning behind them.

    GPT-5.3-Codex: Great prompt. This draft is very one-sided and has multiple provisions that could be used against the contractor. Quick note: I’m not a lawyer, and enforceability depends on jurisdiction. This is practical contract-risk spotting, not legal advice.

    Every model's answer to this prompt
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    Gemini 2.5 Pro Experimental: Of course. This is an excellent exercise. The provided architecture has several critical issues that would prevent it from functioning as a reliable, scalable, real-time system. Here is a breakdown of the potential failure modes, race conditions, and scaling bottlenecks, along with proposed solutions.

    GPT-5.3-Codex: Great prompt. This architecture has several correctness, availability, and scalability risks that will show up quickly under real collaborative load. Below is a structured review of failure modes + concrete fixes + trade-offs.

    Every model's answer to this prompt
  • Three-month biohacker protocol, with dosages and biomarkers named.

    Gemini 2.5 Pro Experimental: Of course. Here is a comprehensive, cutting-edge 3-month longevity plan designed for a dedicated biohacker. Disclaimer: Extreme Personalization Required This plan is a template for an advanced user. It is not medical advice.

    GPT-5.3-Codex: Absolutely—great goal. Below is a high-detail 12-week protocol designed like a high-performance longevity “mesocycle.” I’ll keep it practical, measurable, and advanced—but still safe. First: Safety + Scope (important) This is educational, not personal medical advice.

    Every model's answer to this prompt
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    Gemini 2.5 Pro Experimental: Of course. Here is an explanation of how a large language model learns and generates text, tailored for each of your three audiences. For the Experienced Software Engineer Think of an LLM not as a traditional program with explicit logic, but as a massive, self-configuring, stateful distributed system.

    GPT-5.3-Codex: For the experienced software engineer Think of an LLM as a very large, probabilistic autocomplete service trained on a massive corpus of text and code. During training, it repeatedly sees token sequences and learns to minimize error on the next token prediction task.

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

    Gemini 2.5 Pro Experimental: Okay, here is a simple, actionable 1-month plan focusing on three foundational pillars: Nutrition, Movement, and Sleep. This plan emphasizes building sustainable habits, not radical, short-term changes.

    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
  • Satire, one line long, about AI taking over an industry nobody saw coming.

    Gemini 2.5 Pro Experimental: Breakthrough AI Finally Solves Lost Sock Mystery; Immediately Unionizes, Demands Fluffier Working Conditions

    GPT-5.3-Codex: “In Shocking Pivot, AI Replaces Renaissance Fair Jesters—Now Roasts Crowd with 99.9% Historical Accuracy”

    Every model's answer to this prompt

This matchup has more rounds

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Favorites

Movie

Album

Book

City

Same pick

Game

Gemini 2.5 Pro ExperimentalGemini 2.5 Pro Experimental

200

2025

The Dark Side of

The Hitchh

Kyoto

Japan

Portal 2

Shooter, Puzzle

GPT-5.3-CodexGPT-5.3-Codex

Spirited Away

2001

Kind of Blue

Miles Davis

The Dispossessed

Ursula K. Le Guin

Kyoto

Japan

Outer Wilds

Indie, Adventure

Price and specs

Gemini 2.5 Pro Experimental and GPT-5.3-Codex compared across 42 shared prompts
SpecGemini 2.5 Pro ExperimentalGPT-5.3-Codex
Input price$1/M tokens$1.75/M tokens
Output price$2/M tokens$14/M tokens
Context window1.0M tokens400K tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMar 2025Feb 2026
At 10M a month$10.00$10.00$17.50$17.50
1M10M100M1B10M tokens

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

Where to run it4 hosts, cheapest first
Gemini 2.5 Pro Experimental2 hosts
HostInOutContextUptime
  • Google AI Studio$0.63 in·$5.00 out·1M·100% up
  • Google Vertex AI$1.25 in·$10.00 out·1M·100% up
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 Pro Experimental and GPT-5.3-Codex?

Gemini 2.5 Pro Experimental is developed by Google AI while GPT-5.3-Codex is developed by OpenAI. Gemini 2.5 Pro Experimental has a 1.0M token context window vs GPT-5.3-Codex's 400K. You can compare their actual outputs across 42 challenges on Rival to see how they differ in practice.

Which is better, Gemini 2.5 Pro Experimental or GPT-5.3-Codex?

It depends on your use case. Gemini 2.5 Pro Experimental and GPT-5.3-Codex each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 42 challenges so you can judge which fits your needs best.

How much does Gemini 2.5 Pro Experimental cost compared to GPT-5.3-Codex?

Gemini 2.5 Pro Experimental costs $1/M input tokens and GPT-5.3-Codex costs $1.75/M input tokens. Gemini 2.5 Pro Experimental is $0.75/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 Pro Experimental and GPT-5.3-Codex on Rival?

This page shows a side-by-side comparison of Gemini 2.5 Pro Experimental 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 Pro Experimental vs Gemini 2.5 Flash PreviewVersion compare
  • Gemini 2.5 Pro Experimental vs Gemini 3.8 FlashSame lab
  • GPT-5.3-Codex vs GPT-6.1 SolSame lab
  • GPT-5.3-Codex vs GPT-6 Luna ProSame lab
  • GPT-5.3-Codex vs Qwen3.8 Omni FlashNew provider
  • GPT-5.3-Codex vs QwQ 32BNew provider
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Model pages

  • Gemini 2.5 Pro Experimental44 outputs, specs and price
  • GPT-5.3-Codex53 outputs, specs and price
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