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. GPT-5.1 Codex MaxvsGPT-6 Luna Pro
Updated Sep 2026

GPT-5.1 Codex MaxvsGPT-6 Luna Pro

GPT-6 Luna Pro is the newer model, released after GPT-5.1 Codex Max.

GPT-5.1 Codex Max and GPT-6 Luna Pro compared across 20 shared prompts
SpecGPT-5.1 Codex MaxGPT-6 Luna Pro
Input price—$0.1/M tokens
Output price—$0.5/M tokens
Context window—1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedDec 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 3 of the 20 prompts both answered. Formatting stripped, words untouched.

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

GPT-5.1 Codex Max175 words
Sunset Chickpea & Tomato Skillet A cozy, savory one-pan dish that comes together with staples you likely have on hand. Ingredients (7): 1 can (15 oz) chickpeas, drained and rinsed 1 can (14–15 oz) crushed tomatoes 1 medium onion, finely chopped 2 cloves garlic, minced (or 1 tsp garlic powder) 2 tbsp olive oil 1 tsp…
Read the full answer
GPT-6 Luna Pro127 words
Golden Pantry Pancakes Fluffy, lightly sweet pancakes made with everyday staples. Makes: About 6 small pancakes Prep time: 5 minutes Cook time: 10 minutes Ingredients 1 cup all-purpose flour 1 cup milk 1 egg 2 tablespoons sugar 1 teaspoon baking powder ¼ teaspoon salt 2 tablespoons butter, melted (plus a little for the…
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) –…

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
GPT-6 Luna Pro434 words
Operating and debt schedule Conventions: Interest is calculated on beginning-of-year debt; the 1% Term Loan amortization is 1% of its original $480m principal ($4.8m annually). Mezzanine PIK accrues at 2% annually.
Read the full answer

Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

GPT-5.1 Codex Max386 words
Here's a simple four‑week framework to help you ease into healthier habits. It keeps the focus on three big levers you can control and builds gradually so it feels doable. Key areas: Nourishing food, regular movement, and rest/recovery.
Read the full answer
GPT-6 Luna Pro327 words
A simple 1-month plan for better health and longevity Choose three foundations: eating well, moving regularly, and sleeping consistently. Aim for steady habits, not perfection. Diet: Make nourishing choices easier Week 1: Add one serving of fruit or vegetables to one meal each day.
Read the full answer
Our Verdict
GPT-5.1 Codex Max
GPT-5.1 Codex Max
GPT-6 Luna Pro
GPT-6 Luna Pro

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

GPT-5.1 Codex Max
Input
—
Output
—
GPT-6 Luna Pro
Input
$0.10
Output
$0.50
Where to run it

3 hosts

GPT-5.1 Codex Max1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up
GPT-6 Luna Pro2 hosts
HostInOutContextUptime
Azure AI Foundry$0.10 in·$0.50 out·1.1M·98.6% upOpenAI$0.10 in·$0.50 out·1.1M·99.9% up

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

Research

What we learned reading every model

FAQ

Common questions

Both are developed by OpenAI but target different use cases. You can compare their actual outputs across 20 challenges on Rival to see how they differ in practice.

It depends on your use case. GPT-5.1 Codex Max and GPT-6 Luna Pro each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 20 challenges so you can judge which fits your needs best.

This page shows a side-by-side comparison of GPT-5.1 Codex Max and GPT-6 Luna Pro 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

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

Same lab, same size, long tail

GPT-5.1 Codex Max logoGPT-6 Luna logo
GPT-5.1 Codex Max vs GPT-6 LunaSame lab
GPT-5.1 Codex Max logoGPT-6 Sol logo
GPT-5.1 Codex Max vs GPT-6 SolSame lab
GPT-6 Luna Pro logoGPT-6 Sol Pro logo
GPT-6 Luna Pro vs GPT-6 Sol ProSame lab
GPT-6 Luna Pro logoGPT-6 Sol logo
GPT-6 Luna Pro vs GPT-6 SolSame lab
GPT-6 Luna Pro logoClaude Opus 4 logo
GPT-6 Luna Pro vs Claude Opus 4New provider
GPT-6 Luna Pro logoClaude Opus 4.1 logo
GPT-6 Luna Pro vs Claude Opus 4.1New provider
GPT-6 Luna Pro logoClaude Opus 4.5 logo
GPT-6 Luna Pro vs Claude Opus 4.5New provider
GPT-5.1 Codex Max logoClaude Opus 4.6 logo
GPT-5.1 Codex Max vs Claude Opus 4.6Same size

Model pages

GPT-5.1 Codex Max logo
GPT-5.1 Codex Max53 outputs, specs and price
GPT-6 Luna Pro logo
GPT-6 Luna Pro20 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