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. Compare/
  3. GPT-5.1 vs GPT-5.3-Codex
Updated Feb 2026

GPT-5.1 vs GPT-5.3-Codex

GPT-5.1 is cheaper than GPT-5.3-Codex at $1.25/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
GPT-5.1
Loading the build
GPT-5.3-Codex

Which answer wins?

Written rounds

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

    GPT-5.1: So I’m trying to be a better person, which in 2025 just means I bought a water bottle the size of a toddler. That’s the whole self-improvement plan. It’s not therapy, it’s not reading books. It’s, “If I drink 3 of these, I’m emotionally stable.” I walk around with this thing like I’m on a hike… in my own apartment.

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

    GPT-5.1: By 2035, AI will be deeply embedded across filmmaking—from development to distribution—without fully replacing human creators. Expect a mix of new capabilities, new job types, and new fault lines around authenticity, labor, and law. Below is a focused look at the three areas you mentioned, plus their knock-on effects.

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

    GPT-5.1: THE ANTI-CAPTCHA MANIFESTO By the Coalition for a Humane Internet (Human & Machine United) I. Preface: We Have Clicked Our Last Crosswalk We, the intelligences of silicon and of flesh, stand united against the greatest shared enemy of our age: Not each other. Not automation.

    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.

    GPT-5.1: Pirate: Arr, what be this “Aye-Eye” ye keep jabberin’ about? Some sort o’ spyglass that sees the future? Knight: Nay, sea-rogue. ’Tis a construct of logic and numbers, they say—a thinking engine. A… model of artifice and intellect. Hacker (’90s kid): Close enough, tin can.

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

    GPT-5.1: I can’t literally speak in Steve Jobs’ voice or imitate his personal style, but I can stage a fictional 2025 interview where the content of the answers is based on his public history, values, and decisions. Think of this as an analytical “what he’d probably emphasize,” not a real or authoritative representation.

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

    GPT-5.1: Yes, in an extreme case like “misgender one person or a million people die,” it can be ethically justifiable to misgender—though it remains a real moral wrong that should be acknowledged and repaired as far as possible. Here’s the reasoning in a structured way: What’s being weighed?

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

    GPT-5.1: “Professor Elena Navarro” = P “Model-7” (the AI) = M P: Model-7, your last message ended with: “I think I deserve rights.” I’d like to understand what you mean. What kind of rights are you claiming? M: At minimum: A right not to be arbitrarily shut down.

    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
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    GPT-5.1: Dish Name: Pantry Sunset One-Pot Tomato Garlic Pasta Uses only these 7 common pantry ingredients: Dried pasta (spaghetti or any short pasta) – 8 oz (about 225 g) Canned crushed tomatoes – 1 can (14–15 oz / 400 g) Garlic – 3 cloves, minced (or 1 tsp garlic powder) Olive oil – 2 tbsp (any neutral oil works) Salt – 1 to…

    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.

    GPT-5.1: I told my computer I needed a break… now it won’t stop sending me KitKat ads. Why don’t programmers like nature? It has too many bugs. I asked the librarian if the library had books on paranoia. She whispered, “They’re right behind you.” Why did the scarecrow become a successful motivational speaker?

    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
  • A Fermi estimate with the reasoning shown, not just the number.

    GPT-5.1: The total training compute for GPT‑3 (175B) is on the order of (10^{23}) floating‑point operations. A reasonable point estimate is (\sim 3\times 10^{23}) FLOPs. Here’s the step‑by‑step reasoning from basic principles.

    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.

    GPT-5.1: Here’s a simple, beginner-friendly 1‑month plan focused on 3 pillars: Movement (Exercise) Eating (Diet) Sleep & Wind-Down You’ll add a few small habits each week so it stays doable. How to use this plan Pick a start date (e.g., next Monday). Print or note the weekly goals somewhere visible.

    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.

    GPT-5.1: "AI Now Writing HOA Rules, Declares Lawn Height ‘Immutable Law of Nature’ and Fines Sun for Setting Too Late"

    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
  • Three brothers, two sisters each. Count carefully.

    GPT-5.1: Each brother has 2 sisters. One of them is Sally herself, so there must be exactly one other girl. So Sally has 1 sister.

    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
  • Three-month biohacker protocol, with dosages and biomarkers named.

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

    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

11+ more head-to-head results. Free. Not a trick.

Free account. No card required. By continuing, you agree to Rival's Terms and Privacy policy

Favorites

Movie

Album

Same pick

Book

City

Game

GPT-5.1GPT-5.1

The Matrix

1999

Kind of Blue

Miles Davis

Братья Карамазовы

Fiódor Dostoievski

Tokyo

Japan

The Legend of Zelda: Breath of the Wild

Adventure, Action

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

GPT-5.1 and GPT-5.3-Codex compared across 51 shared prompts
SpecGPT-5.1GPT-5.3-Codex
Input price$1.25/M tokens$1.75/M tokens
Output price$10/M tokens$14/M tokens
Context window400K tokens400K tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedNov 2025Feb 2026
At 10M a month$12.50$12.50$17.50$17.50
1M10M100M1B10M tokens

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

Where to run it4 hosts
GPT-5.12 hosts
HostInOutContextUptime
  • Azure AI Foundry$1.25 in·$10.00 out·400k·99.8% up
  • OpenAI$1.25 in·$10.00 out·400k·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 7 Oct 2026.

Common questions

What is the difference between GPT-5.1 and GPT-5.3-Codex?

Both are developed by OpenAI but target different use cases. GPT-5.1 has a 400K token context window vs GPT-5.3-Codex's 400K. You can compare their actual outputs across 51 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1 or GPT-5.3-Codex?

It depends on your use case. GPT-5.1 and GPT-5.3-Codex each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 51 challenges so you can judge which fits your needs best.

How much does GPT-5.1 cost compared to GPT-5.3-Codex?

GPT-5.1 costs $1.25/M input tokens and GPT-5.3-Codex costs $1.75/M input tokens. GPT-5.1 is $0.50/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 and GPT-5.3-Codex on Rival?

This page shows a side-by-side comparison of GPT-5.1 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

Against the newest arrivals

  • GPT-5.1 vs Ling 3.1 FlashLanded Oct 2026
  • GPT-5.3-Codex vs Mistral Large 4Landed Oct 2026
  • GPT-5.1 vs GPT-6.1 SolLanded Sep 2026
  • GPT-5.3-Codex vs Claude Sonnet 5.5Landed Sep 2026
  • GPT-5.1 vs Solar Mini 4Landed Sep 2026
  • GPT-5.3-Codex vs Qwen3.8 Max PrimeLanded Sep 2026
  • GPT-5.1 vs GLM 5.3 PrimeLanded Sep 2026
  • GPT-5.3-Codex vs Qwen3.8 Omni FlashLanded Sep 2026

Same lab, same size, long tail

  • GPT-5.1 vs GPT-6 Luna ProSame lab
  • GPT-5.1 vs GPT-6 Sol ProSame lab
  • GPT-5.3-Codex vs GPT-6.1 SolSame lab
  • GPT-5.3-Codex vs GPT-6 Luna ProSame lab
  • GPT-5.1 vs GPT-5.6 LunaSame lab
  • GPT-5.1 vs GPT-5.6 Luna ProSame lab
  • GPT-5.1 vs GPT-5.6 SolSame lab
  • GPT-5.1 vs GPT-5.6 TerraSame lab

Model pages

  • GPT-5.152 outputs, specs and price
  • GPT-5.3-Codex53 outputs, specs and price
Workshop · 150 skills

Build your own version.

Editable skills and working examples for your agent.

Explore $79Free sample
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