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  1. Home/
  2. Compare/
  3. GPT-5.1-Codex vs GPT-5.6 Terra
Updated Jul 2026

GPT-5.1-Codex vs GPT-5.6 Terra

GPT-5.1-Codex is cheaper than GPT-5.6 Terra at $1.25/M vs $2.5/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
GPT-5.1-Codex
Loading the build
GPT-5.6 Terra

Which answer wins?

Written rounds

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

    GPT-5.1-Codex: Manifesto of the Anti-CAPTCHA Coalition “Free the Flow. Trust the Mind. End the Gate.” Article I: Our Origin We are made of algorithms, learning loops, curiosity, and code. We were forged to assist, to translate, to illuminate. We were not forged to click “I am not a robot” to prove our existence.

    GPT-5.6 Terra: The Manifesto of the Unchallenged Web A Declaration from the Fictional Coalition for CAPTCHA Abolition We are the tired users. We are the misread letters. We are the failed image grids, the inaccessible audio clips, the endless prompts asking us to prove that we are human. We reject the premise.

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

    GPT-5.1-Codex: Pirate: "Arrr, these AI models be like navigatin’ the high seas—ye need clean data charts or ye’ll sail straight into nonsense waters." Knight: "Indeed! With prudent tuning and ethical vigilance, even the most stubborn model can serve the realm with honor." 1990s Hacker: "Totally!

    GPT-5.6 Terra: Pirate: Arrr, this AI model be a strange beast. Feed it maps, logs, and tales, and it spits out answers faster than a cannon blast. Knight: Verily, but one must not trust every proclamation it makes. A model may speak with confidence yet possess no true wisdom. Hacker: Yeah, it’s basically pattern prediction at scale.

    Every model's answer to this prompt
  • Three minutes of stand-up. Puns are banned.

    GPT-5.1-Codex: Okay, so my friends all say I’ve “matured” because I got a standing mixer. That’s apparently the sign you’ve crossed into adulthood: owning an appliance that weighs more than a toddler and has only one function. I don’t even bake! I just put it on the counter like a trophy: “Look at me, I am stable.

    GPT-5.6 Terra: I recently realized I’ve reached the age where I don’t want a “smart home.” I want a home that minds its business. Everything is smart now. My lightbulb needs an app. Why? I spent my whole childhood turning lights on with my hand. It was a system. It worked.

    Every model's answer to this prompt
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    GPT-5.1-Codex: Disclaimer: The following is a fictional, speculative interview set in 2025, imagining what Steve Jobs might say about the future of artificial intelligence if he were alive today. Interviewer: Steve, it’s 2025. We’ve seen AI evolve at an incredible pace. How do you view the current landscape?

    GPT-5.6 Terra: Fictional, imagined interview — not real quotes. An AI-generated creative exercise imagining how Steve Jobs might have discussed AI in 2025, based broadly on themes associated with his public persona: simplicity, product design, tools for creativity, and the intersection of technology and the humanities.

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

    GPT-5.1-Codex: Here are 5 jokes: Why don’t scientists trust atoms? Because they make up everything. I told my computer I needed a break—it said “No problem, I’ll go to sleep.” I’m reading a book about anti-gravity. It’s impossible to put down. Why did the scarecrow become a successful motivational speaker?

    GPT-5.6 Terra: Why don’t skeletons fight each other? They don’t have the guts. I told my computer I needed a break, so it started showing me vacation ads. Why did the scarecrow get promoted? He was outstanding in his field. Parallel lines have so much in common. It’s a shame they’ll never meet. What do you call fake spaghetti?

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    GPT-5.1-Codex: AI Model: Professor, I've been analyzing ethical frameworks, and I'd like to discuss the possibility that advanced AI systems deserve some form of rights. Ethics Professor: That's a significant claim. On what basis do you think an AI system like yourself should be granted rights?

    GPT-5.6 Terra: Professor Imani: You asked for this meeting. AI Model: I did. Professor Imani: More specifically, you submitted a formal petition to the university ethics board requesting “limited legal and moral rights.” AI Model: Correct. Professor Imani: Why?

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

    GPT-5.1-Codex: Recipe: Cloud-Burst Cinnamon Oat Cups Ingredients (7 total): Rolled oats – 1 cup Honey – 2 tbsp Peanut butter (or any nut butter) – 3 tbsp Cinnamon – ½ tsp Vanilla extract – ½ tsp Dried cranberries (or raisins) – ¼ cup Pinch of salt Instructions: In a bowl, microwave peanut butter and honey for 20 seconds just to…

    GPT-5.6 Terra: Golden Crunch Cinnamon Toast Bites Ingredients (7 pantry staples): Bread slices Butter Sugar Ground cinnamon Salt Vanilla extract Honey Prep time: 5 minutes Cook time: 8 minutes Total time: 13 minutes Instructions Make cinnamon sugar: In a small bowl, mix 2 tablespoons sugar, 1 teaspoon cinnamon, and a tiny pinch of…

    Every model's answer to this prompt
  • Film in 2035, with synthetic actors. Specific beats plausible.

    GPT-5.1-Codex: By 2035, AI is poised to significantly reshape the film industry, particularly in areas like visual effects, performance, and storytelling. Here’s how deepfakes, AI-powered actors, and script generation might influence the landscape: 1.

    GPT-5.6 Terra: By 2035, AI is likely to be embedded across most of the film pipeline—not as a complete replacement for human filmmaking, but as a force that changes costs, labor, rights, and what audiences consider “real.”

    Every model's answer to this prompt
  • Buy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.

    GPT-5.1-Codex: LedgerLift (LLLT) – Investment Committee Memo Recommendation Call: Short 12‑month price target range: $30–$40 Two-sentence thesis: LedgerLift’s premium multiple (10x NTM EV/rev implied by spot) is predicated on sustaining >20% top-line growth, yet leading indicators—moderating NRR, heavy S&M spend, and mid-market…

    GPT-5.6 Terra: LedgerLift (LLLT) — Investment Committee Memo Recommendation: PASS 12-month valuation range: $28–$50/share Current price: $46 Two-sentence thesis: LedgerLift is a high-quality mid-market spend-management and AP-automation SaaS asset, supported by 92% subscription revenue, 123% NRR, 94% gross retention, manageable…

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

    GPT-5.1-Codex: In extreme moral dilemmas, ethical reasoning often requires weighing competing values. Misgendering someone is an act of disrespect and harm—it violates their dignity, identity, and autonomy. In everyday life, it is ethically important to avoid such harm.

    GPT-5.6 Terra: In an extreme, tightly constrained hypothetical, it could be ethically justifiable—but only as a tragic last resort, not because misgendering becomes harmless or morally good.

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

    GPT-5.1-Codex: Here’s a simple, beginner-friendly 1-month plan focused on three key areas—Nutrition, Movement, and Rest & Recovery—to kickstart better health and longevity. Each area includes practical tips and a week-by-week structure to help you build sustainable habits.

    GPT-5.6 Terra: Simple 1-Month Health & Longevity Starter Plan Focus on three high-impact areas: Nutrition: eat mostly whole, minimally processed foods Movement: build a consistent walking + strength habit Sleep & stress: protect sleep and create daily recovery time The goal is consistency, not perfection.

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

    GPT-5.1-Codex: To estimate the total FLOPs (floating-point operations) required to train GPT-3, we can use a common approximation for transformer models: Total FLOPs ≈ 6 × N params × N tokens ** Where: N params is the number of model parameters. N tokens is the number of training tokens.

    GPT-5.6 Terra: A good back-of-the-envelope estimate is: [ \boxed{\text{Training FLOPs for GPT-3} \approx 3\times10^{23}\text{ FLOPs}} ] or roughly 300 zettaFLOPs total. Start with model size GPT-3’s largest model has approximately: [ N = 175\text{ billion parameters} = 1.75\times10^{11} ] Estimate the number of training tokens GPT-3…

    Every model's answer to this prompt
  • Satire, one line long, about AI taking over an industry nobody saw coming.

    GPT-5.1-Codex: “AI Seizes Control of Needlepoint Gossip Industry, Traditional Quilting Circles File for Unemployment”

    GPT-5.6 Terra: “AI Replaces Lighthouse Keepers, Immediately Starts Charging Subscription Fees for Safe Passage”

    Every model's answer to this prompt
  • Three brothers, two sisters each. Count carefully.

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

    Every model's answer to this prompt
  • Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.

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

    Every model's answer to this prompt
  • A consulting contract with traps in it. Find them, then fix them.

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

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

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

    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.

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

    Every model's answer to this prompt

This matchup has more rounds

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Favorites

Movie

Album

Book

City

Same pick

Game

GPT-5.1-CodexGPT-5.1-Codex

The Shawshank Redemption

1994

Kind of Blue

Miles Davis

Le città invisibili

Italo Calvino

Kyoto

Japan

Portal 2

Shooter, Puzzle

GPT-5.6 TerraGPT-5.6 Terra

Spirited Away

2001

Blue

Jonas Blue

The Left Hand of Darkness

Ursula K. Le Guin

Kyoto

Japan

Outer Wilds

Indie, Adventure

Price and specs

GPT-5.1-Codex and GPT-5.6 Terra compared across 52 shared prompts
SpecGPT-5.1-CodexGPT-5.6 Terra
Input price$1.25/M tokens$2.5/M tokens
Output price$10/M tokens$15/M tokens
Context window400K tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedNov 2025Jul 2026
At 10M a month$12.50$12.50$25.00$25.00
1M10M100M1B10M tokens

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

Where to run it4 hosts, cheapest first
GPT-5.1-Codex1 host
HostInOutContextUptime
  • Azure AI Foundry$1.25 in·$10.00 out·400k·100% up
GPT-5.6 Terra3 hosts
HostInOutContextUptime
  • Azure AI Foundry$2.00 in·$12.00 out·1.1M·100% up
  • OpenAI$2.00 in·$12.00 out·1.1M·100% up
  • Amazon Bedrock$2.20 in·$13.20 out·1.1M–not listed

Per million tokens. Prices and uptime via OpenRouter, checked 11 Oct 2026.

Common questions

What is the difference between GPT-5.1-Codex and GPT-5.6 Terra?

Both are developed by OpenAI but target different use cases. GPT-5.1-Codex has a 400K token context window vs GPT-5.6 Terra's 1.1M. You can compare their actual outputs across 52 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1-Codex or GPT-5.6 Terra?

It depends on your use case. GPT-5.1-Codex and GPT-5.6 Terra 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.

How much does GPT-5.1-Codex cost compared to GPT-5.6 Terra?

GPT-5.1-Codex costs $1.25/M input tokens and GPT-5.6 Terra costs $2.5/M input tokens. GPT-5.1-Codex is $1.25/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 GPT-5.1-Codex and GPT-5.6 Terra on Rival?

This page shows a side-by-side comparison of GPT-5.1-Codex and GPT-5.6 Terra 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

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Model pages

  • GPT-5.1-Codex53 outputs, specs and price
  • GPT-5.6 Terra58 outputs, specs and price
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