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-5.1vsGPT-6 Luna Pro
Updated Sep 2026

GPT-5.1vsGPT-6 Luna Pro

GPT-6 Luna Pro is cheaper than GPT-5.1 at $0.1/M vs $1.25/M input tokens.

GPT-5.1 and GPT-6 Luna Pro compared across 20 shared prompts
SpecGPT-5.1GPT-6 Luna Pro
Input price$1.25/M tokens$0.1/M tokens
Output price$10/M tokens$0.5/M tokens
Context window400K tokens1.1M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedNov 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-5.1200 words
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…
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

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-5.1979 words
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.
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

Favorite Game

I know you're an AI and don't truly have personal preferences, but if you had to pick one video game as your all-time favorite, which would…

GPT-5.18 words
The Legend of Zelda Breath of the Wild
Read the full answer
GPT-6 Luna Pro8 words
The Legend of Zelda: Breath of the Wild
Read the full answer
Our Verdict
GPT-5.1
GPT-5.1
GPT-6 Luna Pro
GPT-6 Luna Pro

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

GPT-6 Luna Pro costs 20x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5.1
Input
$1.25
Output
$10.00
GPT-6 Luna Pro
Input
$0.10
13× cheaper
Output
$0.50
20× cheaper

GPT-6 Luna Pro is cheaper on both: 13× input, 20× output.

Where to run it

4 hosts

GPT-5.12 hosts
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% upOpenAI$1.25 in·$10.00 out·400k·99.8% 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. GPT-5.1 has a 400K token context window vs GPT-6 Luna Pro's 1.1M. 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 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.

GPT-5.1 costs $1.25/M input tokens and GPT-6 Luna Pro costs $0.1/M input tokens. GPT-6 Luna Pro is $1.15/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of GPT-5.1 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 logoSolar Mini 4 logo
GPT-5.1 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 logoGLM 5.3 Prime logo
GPT-5.1 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 logoCommand A+ logo
GPT-5.1 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 logoGPT-6 Sol Pro logo
GPT-5.1 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 logoGPT-6 Luna logo
GPT-5.1 vs GPT-6 LunaSame lab
GPT-5.1 logoGPT-6 Sol logo
GPT-5.1 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-5.1 logoQwen3.8 Max Prime logo
GPT-5.1 vs Qwen3.8 Max PrimeNew provider
GPT-5.1 logoQwen3.8 Omni Flash logo
GPT-5.1 vs Qwen3.8 Omni FlashNew provider
GPT-6 Luna Pro logoQwQ 32B logo
GPT-6 Luna Pro vs QwQ 32BSame size
GPT-5.1 logoRing 2.6 1T logo
GPT-5.1 vs Ring 2.6 1TSame size

Model pages

GPT-5.1 logo
GPT-5.152 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