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-6 Luna ProvsMercury 2.5 Preview
Updated Sep 2026

GPT-6 Luna ProvsMercury 2.5 Preview

Mercury 2.5 Preview is cheaper than GPT-6 Luna Pro at $0.04/M vs $0.1/M input tokens.

GPT-6 Luna Pro and Mercury 2.5 Preview compared across 20 shared prompts
SpecGPT-6 Luna ProMercury 2.5 Preview
Input price$0.1/M tokens$0.04/M tokens
Output price$0.5/M tokens$0.15/M tokens
Context window1.1M tokens260K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedSep 2026Aug 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 20 prompts both answered. Formatting stripped, words untouched.

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-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
Mercury 2.5 Preview176 words
Here is a straightforward 4-week roadmap designed to build sustainable habits without overwhelming you. Core Pillars Nutrition: Focus on whole foods and hydration. Activity: Prioritize consistent movement over intensity. Restoration: Protect sleep quality and manage energy.
Read the full answer

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-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
Mercury 2.5 Preview186 words
Dish Name: Rustic Sun-Dried Pasta Ingredients (7 Pantry Staples): Spaghetti (or any long pasta) Canned crushed tomatoes Olive oil Garlic powder Dried oregano Salt Black pepper Prep Time: 5 minutes Cook Time: 15 minutes Total Time: 20 minutes Instructions: Boil the Pasta: Bring a large pot of salted water to a boil.
Read the full answer

Explain Like I'm a Specific Expert

Explain how a large language model (like GPT or Claude) learns and generates text to each of these three audiences: 1. **An experienced…

GPT-6 Luna Pro892 words
For an experienced software engineer Think of a language model as a system trained to continue sequences: given a prefix of text, it assigns probabilities to possible next tokens (tokens are pieces of words, not necessarily whole words) and learns to make the observed continuation likely.
Read the full answer
Mercury 2.5 Preview608 words
For the Experienced Software Engineer Think of training as a massive distributed job where the model is a stateful service learning to minimize error on a specific objective function. Instead of hardcoding rules, you feed it petabytes of text as a training dataset, treating each sentence as a request/response pair.
Read the full answer

Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

GPT-6 Luna Pro2,116 words
This agreement is heavily one-sided. Several terms let the Client expand the work, delay or deny payment, claim ownership of the Contractor’s existing materials, and expose the Contractor to potentially unlimited liability.
Read the full answer
Mercury 2.5 Preview500 words
Disclaimer: I am an AI assistant and cannot provide legal advice. Consult a qualified attorney before signing any contract. Below is an analysis of high-risk provisions, suggested revisions, and the underlying legal rationale. Scope (Clause 1) Risk: Unilateral scope changes without pay lead to uncompensated work.
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-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
Mercury 2.5 Preview299 words
Year-by-Year Model (FY2026–FY2030) Metric FY2026 FY2027 FY2028 FY2029 FY2030 Revenue $972m $1,040m $1,102m $1,158m $1,215m EBITDA $136m $156m $176m $191m $207m Cash Interest (Term) $43.2m $41.1m $37.6m $33.4m $28.2m Cash Interest (Mezz) $21.6m $21.6m $21.6m $21.6m $21.6m Cash Taxes (25%) $17.8m $23.3m $29.3m $34.7m…
Read the full answer

Startup Pitch Teardown

Here's a pitch deck summary for a startup called "MindMeld AI": **Slide 1 - Vision:** "We're building the future of human-AI collaboration.…

GPT-6 Luna Pro401 words
“94% accuracy” and “works with any language, any device” Why it’s weak: “Accuracy” is undefined. It could mean classifying a small set of prompted words in a controlled lab—not reliably generating free-form text.
Read the full answer
Mercury 2.5 Preview312 words
Here are the three weakest claims in the MindMeld AI pitch, along with analysis and recommendations for improvement. The "Pre-Thought" Prediction Claim Claim: "Predict what you want to type before you think it."
Read the full answer
Our Verdict
GPT-6 Luna Pro
GPT-6 Luna Pro
Mercury 2.5 Preview
Mercury 2.5 PreviewRunner-up

Not enough votes to call it. On the specs, GPT-6 Luna Pro has the edge: bigger model tier, bigger context window, major provider backing.

Mercury 2.5 Preview costs 3.3x less per token.

Slight edge

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-6 Luna Pro
Input
$0.10
Output
$0.50
Mercury 2.5 Preview
Input
$0.04
2.5× cheaper
Output
$0.15
3.3× cheaper

Mercury 2.5 Preview is cheaper on both: 2.5× input, 3.3× output.

Where to run it

3 hosts

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
Mercury 2.5 Preview1 host
HostInOutContextUptime
Inception$0.04 in·$0.15 out·260k·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

GPT-6 Luna Pro is developed by OpenAI while Mercury 2.5 Preview is developed by Inception. GPT-6 Luna Pro has a 1.1M token context window vs Mercury 2.5 Preview's 260K. 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-6 Luna Pro and Mercury 2.5 Preview 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-6 Luna Pro costs $0.1/M input tokens and Mercury 2.5 Preview costs $0.04/M input tokens. Mercury 2.5 Preview is $0.06/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-6 Luna Pro and Mercury 2.5 Preview 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-6 Luna Pro logoSolar Mini 4 logo
GPT-6 Luna Pro vs Solar Mini 4Landed Sep 2026
Mercury 2.5 Preview logoQwen3.8 Max Prime logo
Mercury 2.5 Preview vs Qwen3.8 Max PrimeLanded Sep 2026
GPT-6 Luna Pro logoGLM 5.3 Prime logo
GPT-6 Luna Pro vs GLM 5.3 PrimeLanded Sep 2026
Mercury 2.5 Preview logoQwen3.8 Omni Flash logo
Mercury 2.5 Preview vs Qwen3.8 Omni FlashLanded Sep 2026
GPT-6 Luna Pro logoCommand A+ logo
GPT-6 Luna Pro vs Command A+Landed Sep 2026
Mercury 2.5 Preview logoClaude Opus 5.5 logo
Mercury 2.5 Preview vs Claude Opus 5.5Landed Sep 2026
GPT-6 Luna Pro logoGPT-6 Sol Pro logo
GPT-6 Luna Pro vs GPT-6 Sol ProLanded Sep 2026
Mercury 2.5 Preview logoGPT-6 Luna logo
Mercury 2.5 Preview vs GPT-6 LunaLanded Sep 2026

Same lab, same size, long tail

GPT-6 Luna Pro logoGPT-6 Luna logo
GPT-6 Luna Pro vs GPT-6 LunaSame lab
GPT-6 Luna Pro logoGPT-6 Sol logo
GPT-6 Luna Pro vs GPT-6 SolSame lab
Mercury 2.5 Preview logoMercury 2.5 logo
Mercury 2.5 Preview vs Mercury 2.5Same lab
Mercury 2.5 Preview logoMercury logo
Mercury 2.5 Preview vs MercurySame lab
GPT-6 Luna Pro logoDeepSeek V4 Pro logo
GPT-6 Luna Pro vs DeepSeek V4 ProNew provider
GPT-6 Luna Pro logoDeepSeek V4 Pro 0813 logo
GPT-6 Luna Pro vs DeepSeek V4 Pro 0813New provider
Mercury 2.5 Preview logoDeepSeek V4.1 Flash logo
Mercury 2.5 Preview vs DeepSeek V4.1 FlashNew provider
GPT-6 Luna Pro logoDevstral 2 2512 logo
GPT-6 Luna Pro vs Devstral 2 2512New provider

Model pages

GPT-6 Luna Pro logo
GPT-6 Luna Pro20 outputs, specs and price
Mercury 2.5 Preview logo
Mercury 2.5 Preview58 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