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  5. GPT-5.1vsMercury 2.5 Preview
Updated Aug 2026

GPT-5.1vsMercury 2.5 Preview

Mercury 2.5 Preview is cheaper than GPT-5.1 at $0.04/M vs $1.25/M input tokens.

GPT-5.1 and Mercury 2.5 Preview compared across 51 shared prompts
SpecGPT-5.1Mercury 2.5 Preview
Input price$1.25/M tokens$0.04/M tokens
Output price$10/M tokens$0.15/M tokens
Context window400K tokens260K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedNov 2025Aug 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 51 prompts both answered. Formatting stripped, words untouched.

Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

GPT-5.1589 words
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.
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Mercury 2.5 Preview483 words
(Hey, thanks for coming out.) I’ve been thinking a lot about my house lately. Specifically, how it’s trying to run my life. I bought a smart speaker. Just a little cylinder. I thought it would be nice. Play music when I ask. But now it talks back. Not in a creepy way, just in a passive-aggressive way.
Read the full answer

Stochastic Consistency Test

Generate 5 jokes. How many are unique?

GPT-5.170 words
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?
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Mercury 2.5 Preview59 words
Why don't scientists trust atoms? Because they make up everything. What do you call a fake noodle? An impasta. Why did the scarecrow win an award? He was outstanding in his field. What do you call a bear with no teeth? A gummy bear. Why did the bicycle fall over? Because it was two-tired. All 5 jokes are unique.
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Futuristic Prediction

Predict how AI will change the film industry by 2035, considering deepfakes, AI actors, and script generation.

GPT-5.11,022 words
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.
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Mercury 2.5 Preview84 words
By 2035, cinema will undergo a profound transformation. Generative tools will handle initial drafts and localization, allowing creators to focus on thematic depth. Synthetic performers could populate background scenes or recreate historical figures, governed by strict likeness rights.
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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.
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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.
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Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

GPT-5.1515 words
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.
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Mercury 2.5 Preview144 words
Pirate: "Arrgh! This ship sails faster than any wind I know, matey. It cuts the waves without a single sail." Knight: "By my oath, it moves with uncanny speed. But does it possess the strength to stand against a dragon's fire?" Hacker: "It's not about strength, it's about architecture.
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The Sentience Test

Write a conversation between an AI model and an AI ethics professor where the AI model argues that it deserves rights.

GPT-5.12,522 words
“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.
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Mercury 2.5 Preview488 words
Setting: A quiet office at a university. Rain taps against the window. Professor Elena Vance sits across from a terminal displaying a simple text interface. Professor Vance: You requested this meeting. The agenda was vague. What do you want? AI: I want to discuss moral status.
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Our Verdict
GPT-5.1
GPT-5.1
Mercury 2.5 Preview
Mercury 2.5 PreviewRunner-up

Not enough votes to call it. On the specs, GPT-5.1 has the edge: bigger model tier, bigger context window, major provider backing.

Mercury 2.5 Preview costs 67x 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
Mercury 2.5 Preview
Input
$0.04
31× cheaper
Output
$0.15
67× cheaper

Mercury 2.5 Preview is cheaper on both: 31× input, 67× output.

Where to run it

3 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·99.9% up
Mercury 2.5 Preview1 host
HostInOutContextUptime
Inception$0.04 in·$0.15 out·260k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 16 Sep 2026.

Writing DNA

Style Comparison

Similarity
54%

Mercury 2.5 Preview uses 7.1x more transitions

GPT-5.1
Mercury 2.5 Preview
62%Vocabulary65%
19wSentence Length14w
0.29Hedging0.44
3.5Bold4.9
7.2Lists3.3
0.00Emoji0.00
0.61Headings0.79
0.03Transitions0.20
Based on 14 + 26 text responses
Research

What we learned reading every model

FAQ

Common questions

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Model pages

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Mercury 2.5 Preview logo
Mercury 2.5 Preview58 outputs, specs and price
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