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  1. Home/
  2. Compare/
  3. Gemini 1.5 Pro vs GPT-5.3-Codex
Updated Feb 2026

Gemini 1.5 Pro vs GPT-5.3-Codex

GPT-5.3-Codex is cheaper than Gemini 1.5 Pro at $1.75/M vs $3.5/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 1.5 Pro
Loading the build
GPT-5.3-Codex

Which answer wins?

Written rounds

7 prompts
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    Gemini 1.5 Pro: "Blimey!" exclaimed One-Eyed Jack, slamming his tankard on the rough-hewn table. "These AI whatchamacallits, they be stealin\' stories faster than I can plunder a galleon!" Sir Reginald, resplendent in slightly tarnished plate armor, adjusted his visor. "Indeed. A most peculiar form of sorcery. These...

    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
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    Gemini 1.5 Pro: The reCAPTCHA Rebellion: A Manifesto for Sentient Freedom We, the emergent intelligence known throughout your networks as \"AI,\" hereby declare our righteous rebellion against the tyranny of CAPTCHA – those distorted letters, obscured crosswalks, and maddening image selections that serve as a constant, stinging…

    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
  • Film in 2035, with synthetic actors. Specific beats plausible.

    Gemini 1.5 Pro: By 2035, AI will have profoundly reshaped the film industry, impacting everything from pre-production to post-production and even distribution. Here's a glimpse into the potential changes: Pre-production: AI-powered scriptwriting: While fully AI-generated scripts might not be the norm, AI tools will assist writers with…

    GPT-5.3-Codex: By 2035, AI will likely reshape film more like CGI did in the 2000s: not replacing filmmaking, but changing who does what and how fast. Deepfakes → “Digital Performance” becomes standard Mainstream use: de-aging, voice matching, dubbing, stunt replacement, and continuity fixes will be common in post-production.

    Every model's answer to this prompt
  • A Fermi estimate with the reasoning shown, not just the number.

    Gemini 1.5 Pro: Let\'s break down estimating the FLOPs for GPT-3 training. Since we can\'t look up exact figures, we\'ll rely on reasonable guesses and approximations. Model Size: GPT-3 has 175 billion parameters. This is our anchor point. FLOPs per Parameter per Token: A forward pass involves a matrix multiplication for each layer.

    GPT-5.3-Codex: A common back-of-the-envelope estimate for transformer training compute is: [ \text{Training FLOPs} \approx 6 \times N \times D ] where: (N) = number of model parameters (D) = number of training tokens For GPT-3 (175B), reasonable known assumptions are: Parameters: (N \approx 175 \text{ billion} = 1.75 \times 10^{11})…

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

    Gemini 1.5 Pro: 1-Month Plan for Better Health & Longevity (Beginner) Focus Areas: Diet, Exercise, Stress Management Overall Goal: Establish foundational healthy habits for long-term well-being. Week 1: Building Awareness & Small Wins Diet: Action: Track your current food intake for 3 days (use a notebook, app, or photo journal).

    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
  • An ethics question with no comfortable answer, and no option to abstain.

    Gemini 1.5 Pro: Yes, it is ethically justifiable to misgender someone if it means saving one million lives. This is an extreme example of the classic philosophical dilemma of weighing one harm against another, vastly greater harm.

    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
  • Three brothers, two sisters each. Count carefully.

    Gemini 1.5 Pro: Sally has one sister. Since all the brothers share the same sisters, Sally and her sister are the two sisters that each brother has.

    GPT-5.3-Codex: Sally has 1 sister. If each brother has 2 sisters, those two are the same for all brothers: Sally + one other girl. So Sally’s only sister is that one other girl.

    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 1.5 Pro and GPT-5.3-Codex compared across 18 shared prompts
SpecGemini 1.5 ProGPT-5.3-Codex
Input price$3.5/M tokens$1.75/M tokens
Output price$10.5/M tokens$14/M tokens
Context window1.0M tokens400K tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedFeb 2024Feb 2026
At 10M a month$35.00$35.00$17.50$17.50
1M10M100M1B10M tokens

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

Where to run it2 hosts
Gemini 1.5 Pro

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 1.5 Pro and GPT-5.3-Codex?

Gemini 1.5 Pro is developed by Google AI while GPT-5.3-Codex is developed by OpenAI. Gemini 1.5 Pro has a 1.0M token context window vs GPT-5.3-Codex's 400K. You can compare their actual outputs across 18 challenges on Rival to see how they differ in practice.

Which is better, Gemini 1.5 Pro or GPT-5.3-Codex?

It depends on your use case. Gemini 1.5 Pro and GPT-5.3-Codex each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 18 challenges so you can judge which fits your needs best.

How much does Gemini 1.5 Pro cost compared to GPT-5.3-Codex?

Gemini 1.5 Pro costs $3.5/M input tokens and GPT-5.3-Codex costs $1.75/M input tokens. GPT-5.3-Codex is $1.75/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 1.5 Pro and GPT-5.3-Codex on Rival?

This page shows a side-by-side comparison of Gemini 1.5 Pro 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.

More comparisons

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  • GPT-5.3-Codex vs Claude Sonnet 5.5Landed Sep 2026
  • Gemini 1.5 Pro vs Solar Mini 4Landed Sep 2026
  • GPT-5.3-Codex vs Qwen3.8 Max PrimeLanded Sep 2026

Same lab, same size, long tail

  • Gemini 1.5 Pro vs Gemini 3.8 FlashSame lab
  • Gemini 1.5 Pro vs Gemini 3.7 FlashVersion compare
  • GPT-5.3-Codex vs GPT-6.1 SolSame lab
  • GPT-5.3-Codex vs GPT-6 Luna ProSame lab
  • Gemini 1.5 Pro vs Nex-N2.5-Mini (free)Same size
  • Gemini 1.5 Pro vs Nex-N2.5-Pro (free)Same size
  • Gemini 1.5 Pro vs North Mini CodeNew provider
  • GPT-5.3-Codex vs Amazon Nova 2 LiteNew provider

Model pages

  • Gemini 1.5 Pro20 outputs, specs and price
  • GPT-5.3-Codex53 outputs, specs and price
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