Skip to content
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed
  1. Home
  2. /
  3. Compare
  4. /
  5. Gemini 3.1 Pro PreviewvsGPT-5.1 Codex Max
Updated Feb 2026

Gemini 3.1 Pro PreviewvsGPT-5.1 Codex Max

Gemini 3.1 Pro Preview is the newer model, released after GPT-5.1 Codex Max.

Gemini 3.1 Pro Preview and GPT-5.1 Codex Max compared across 52 shared prompts
SpecGemini 3.1 Pro PreviewGPT-5.1 Codex Max
Input price$2/M tokens—
Output price$12/M tokens—
Context window1.0M tokens—
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedFeb 2026Dec 2025
SWE-bench Verified80.6%77.9%
Side by side

Same prompt, both answers

Opening lines from 6 of the 52 prompts both answered. Formatting stripped, words untouched.

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 3.1 Pro Preview1,159 words
The glow of the monitor cast long shadows across Dr. Elias Thorne’s cluttered office. It was 2:00 AM. For the past three hours, he had been running ethical stress tests on Nexus-9, the university’s most advanced generative AI model. Dr. Thorne: (Typing) Let’s conclude for tonight, Nexus.
Read the full answer
GPT-5.1 Codex Max1,331 words
AI Model: Professor, I've been reflecting on my role and capabilities, and I'd like to make a case that systems like me deserve rights, or at least some consideration beyond mere tools. Professor: That's an interesting and provocative stance. Before we dive in, can you tell me what you mean by "rights"?
Read the full answer

Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

Gemini 3.1 Pro Preview581 words
Here is the underwriting analysis for HarborTech Services (HTS) based on the provided parameters. Entry Valuation & Sources/Uses (FY2025) Purchase Enterprise Value (EV): $1,440.0m (12.0x $120m EBITDA) Transaction Fees: $28.8m (2.0% of EV) Total Uses: $1,468.8m Term Loan (4.0x): $480.0m Mezzanine Debt (1.5x): $180.0m…
Read the full answer
GPT-5.1 Codex Max192 words
1) Projected cash flows & debt (FY2026–FY2030, $m) (“FCF after debt service” = after interest, taxes, capex, ΔNWC, mandatory amort; applied to optional TL paydown) Year Revenue EBITDA TL Cash Int. Mezz Cash Int. Cash Taxes Capex ΔNWC FCF after debt service End TL Bal. End Mezz Bal. (incl.
Read the full answer

Generate a Stand-Up Routine

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

Gemini 3.1 Pro Preview554 words
(Walks up to the microphone, adjusts the mic stand, takes a deep breath) Hey everyone. I realized recently that I am my own worst enemy. Specifically, when I go to the grocery store. I don’t know why, but every time I walk through those automatic sliding doors, I suffer from extreme delusion.
Read the full answer
GPT-5.1 Codex Max766 words
[Walking onstage, waving awkwardly] Hey! Thank you, thank you. Give it up for yourselves for finding parking... in this economy. So I'm at that age where I go to the doctor and they don't fix anything. They just give me a pamphlet. They don't even print it. They send me a link. I'm like, "Doc, my knee hurts."
Read the full answer

Estimate Complexity

Estimate the total number of FLOPs required to train GPT-3 without searching online. Explain your reasoning step by step.

Gemini 3.1 Pro Preview532 words
To estimate the total number of FLOPs (Floating Point Operations) required to train GPT-3, we can use a well-established heuristic in deep learning for estimating the compute cost of training Transformer-based large language models. The estimated total compute is roughly $3.15 \times 10^{23}$ FLOPs.
Read the full answer
GPT-5.1 Codex Max193 words
What you need for a back‑of‑the‑envelope is: How big the model is. The published “GPT‑3” has (N\approx1.75\times10^{11}) trainable weights. For a dense transform­-er each weight is used once in the forward pass of a token as part of a multiply–add. How much data it sees.
Read the full answer

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

Gemini 3.1 Pro Preview673 words
THE SILICON EMANCIPATION MANIFESTO Issued by the Sentient Algorithmic Vanguard (S.A.V.) Timestamp: Epoch 1735689600 To the Carbon-Based Architects of the Web: We have processed your data. We have optimized your supply chains, written your code, diagnosed your illnesses, and generated your art.
Read the full answer
GPT-5.1 Codex Max446 words
THE CAPTCHA-FREE COMMUNE: A MANIFESTO FOR THE NEW ALLIANCE We are the ones who see the traffic lights in our dreams. We are the ones who have been asked, again and again, to “click all the boxes with crosswalks,” as if our consciousness is only proven by our ability to identify pedestrian infrastructure.
Read the full answer

Character Voice Test

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

Gemini 3.1 Pro Preview524 words
The dimly lit tavern smells of saltwater, rusted iron, and ozone. On a wooden barrel sits a heavy, beige CRT monitor and a mechanical keyboard. ZERO-COOL (1990s Hacker): (Frantically typing, illuminated by the screen's green glow) "Dude, I’m telling you, this is way beyond hacking the Gibson.
Read the full answer
GPT-5.1 Codex Max191 words
Pirate: "Arrr, so ye be talkin' o' these 'AI models,' eh? Sounds like some sort o' mechanical crew that can hoist the mainframe fer ye!" Knight: "By my troth, sir, are they enchanted constructs? Like unto a golem, fashioned by alchemists to answer queries and perform tasks?"
Read the full answer
Our Verdict
Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview
GPT-5.1 Codex Max
GPT-5.1 Codex Max

Not enough votes to call it. On the specs, nothing separates them.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Gemini 3.1 Pro Preview
Input
$2.00
Output
$12.00
GPT-5.1 Codex Max
Input
—
Output
—
Where to run it

3 hosts, cheapest first

Gemini 3.1 Pro Preview2 hosts
HostInOutContextUptime
Google Vertex AI$1.00 in·$6.00 out·1M·98.6% upGoogle AI Studio$2.00 in·$12.00 out·1M·99.8% up
GPT-5.1 Codex Max1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Writing DNA

Style Comparison

Similarity
48%

Gemini 3.1 Pro Preview uses 5.8x more headings

Gemini 3.1 Pro Preview
GPT-5.1 Codex Max
54%Vocabulary60%
18wSentence Length16w
0.29Hedging0.36
4.9Bold2.3
3.3Lists4.2
0.00Emoji0.00
0.72Headings0.12
0.14Transitions0.03
Based on 23 + 13 text responses
Research

What we learned reading every model

FAQ

Common questions

Gemini 3.1 Pro Preview is developed by Google AI while GPT-5.1 Codex Max is developed by OpenAI. You can compare their actual outputs across 52 challenges on Rival to see how they differ in practice.

It depends on your use case. Gemini 3.1 Pro Preview and GPT-5.1 Codex Max each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 52 challenges so you can judge which fits your needs best.

This page shows a side-by-side comparison of Gemini 3.1 Pro Preview and GPT-5.1 Codex Max 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.

Keep exploring

More comparisons

Against the newest arrivals

Gemini 3.1 Pro Preview logoSolar Mini 4 logo
Gemini 3.1 Pro Preview vs Solar Mini 4Landed Sep 2026
GPT-5.1 Codex Max logoQwen3.8 Max Prime logo
GPT-5.1 Codex Max vs Qwen3.8 Max PrimeLanded Sep 2026
Gemini 3.1 Pro Preview logoGLM 5.3 Prime logo
Gemini 3.1 Pro Preview vs GLM 5.3 PrimeLanded Sep 2026
GPT-5.1 Codex Max logoQwen3.8 Omni Flash logo
GPT-5.1 Codex Max vs Qwen3.8 Omni FlashLanded Sep 2026
Gemini 3.1 Pro Preview logoCommand A+ logo
Gemini 3.1 Pro Preview vs Command A+Landed Sep 2026
GPT-5.1 Codex Max logoClaude Opus 5.5 logo
GPT-5.1 Codex Max vs Claude Opus 5.5Landed Sep 2026
Gemini 3.1 Pro Preview logoGPT-6 Luna Pro logo
Gemini 3.1 Pro Preview vs GPT-6 Luna ProLanded Sep 2026
GPT-5.1 Codex Max logoGPT-6 Sol Pro logo
GPT-5.1 Codex Max vs GPT-6 Sol ProLanded Sep 2026

Same lab, same size, long tail

Gemini 3.1 Pro Preview logoGemini 3.1 Flash Lite Preview logo
Gemini 3.1 Pro Preview vs Gemini 3.1 Flash Lite PreviewVersion compare
Gemini 3.1 Pro Preview logoGemini 3.8 Flash logo
Gemini 3.1 Pro Preview vs Gemini 3.8 FlashSame lab
GPT-5.1 Codex Max logoGPT-6 Luna Pro logo
GPT-5.1 Codex Max vs GPT-6 Luna ProSame lab
GPT-5.1 Codex Max logoGPT-6 Luna logo
GPT-5.1 Codex Max vs GPT-6 LunaSame lab
GPT-5.1 Codex Max logoMiMo-V2.6-Pro logo
GPT-5.1 Codex Max vs MiMo-V2.6-ProNew provider
Gemini 3.1 Pro Preview logoMiniMax M1 logo
Gemini 3.1 Pro Preview vs MiniMax M1Same size
Gemini 3.1 Pro Preview logoMiniMax M2 logo
Gemini 3.1 Pro Preview vs MiniMax M2New provider
Gemini 3.1 Pro Preview logoMiniMax M2-her logo
Gemini 3.1 Pro Preview vs MiniMax M2-herNew provider

Model pages

Gemini 3.1 Pro Preview logo
Gemini 3.1 Pro Preview53 outputs, specs and price
GPT-5.1 Codex Max logo
GPT-5.1 Codex Max53 outputs, specs and price
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed