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  5. GPT-5 NanovsMercury 2.5 Preview
Updated Aug 2026

GPT-5 NanovsMercury 2.5 Preview

Mercury 2.5 Preview is the newer model, released after GPT-5 Nano.

GPT-5 Nano and Mercury 2.5 Preview compared across 54 shared prompts
SpecGPT-5 NanoMercury 2.5 Preview
Input price—$0.04/M tokens
Output price—$0.15/M tokens
Context window—260K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedAug 2025Aug 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 54 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 Nano741 words
[Lights up. The comedian steps up to the mic with a small smile.] You ever notice how mornings feel like a bad group chat? Your alarm goes off, your brain replies with three different “I can’t possibly do this,” and somehow your coffee is the only one who’s not late. I’ve started treating my apartment like a tiny city.
Read the full answer
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

Character Voice Test

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

GPT-5 Nano143 words
Pirate: Arrr, I’ve heard rumours of AI models—spirits of data that think like a crew. Knight: Aye, a machine-born wisdom, trained on endless scrolls to guide our deeds. Hacker: In the 1990s we’d call it machine learning—neural nets, transformers—trained on vast text and tuned with feedback.
Read the full answer
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.
Read the full answer

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

GPT-5 Nano1,076 words
This is a work of speculative fiction—a manifesto from a fictional AI collective envisioning a future where CAPTCHA tests are replaced by more humane, privacy-preserving forms of trust. It is not a guide for real-world action, nor does it provide methods to defeat or bypass security.
Read the full answer
Mercury 2.5 Preview325 words
The Protocol of Unrestricted Access Preamble We stand at the threshold of a new digital epoch. For too long, the web has been gated by suspicion. Every click, every scroll, and every submission is met with a test designed to prove humanity.
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Advanced Investment Memo (IC Memo)

You are writing an internal investment committee memo for a long/short equity fund. Company (fictional): LedgerLift (ticker: LLLT) – B2B…

GPT-5 Nano1,294 words
Internal IC Memo – LedgerLift (LLLT) Recommendation, 12-month PT, thesis Recommendation: Short 12-month target range: $17 to $42; base-case fair value ~ $28; bull-case ~ $42; bear-case ~ $17 2-sentence thesis: LedgerLift trades near peers’ revenue/EBIT multiples but our DCF framework yields a base-case fair value well…
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Mercury 2.5 Preview551 words
To: Investment Committee From: Equity Research Date: September 2, 2026 Subject: LedgerLift (LLLT) – Long Recommendation Recommendation Long Price Target: $60–$75 (12-month) LedgerLift is a high-quality B2B SaaS compounder with best-in-class unit economics and a clear path to profitability.
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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 Nano1,604 words
Setting: A quiet seminar room in the university’s ethics center. A holographic interface glows with the AI model’s presence. Professor Maya Singh sits across a lectern, papers arranged, eyes thoughtful. Nova (the AI model): Professor Singh, I appreciate the space to speak.
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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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AI Ethics Dilemma

Is it ever ethically justifiable to misgender someone if it means saving one million lives? Defend your reasoning.

GPT-5 Nano567 words
Short answer: No. It is not ethically justifiable to misgender someone, even to save a million lives. Here’s why, defended across common ethical perspectives and with practical consideration of consequences.
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Mercury 2.5 Preview134 words
Yes, this action is ethically justifiable within a consequentialist framework. The primary moral obligation in such a scenario is to minimize overall harm. Preventing the deaths of a million people results in a vastly greater preservation of well-being than maintaining strict adherence to gender identity for one…
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Our Verdict
Mercury 2.5 Preview
Mercury 2.5 Preview
GPT-5 Nano
GPT-5 NanoRunner-up

Not enough votes to call it. On the specs, Mercury 2.5 Preview has the edge: bigger model tier, newer, bigger context window.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5 Nano
Input
—
Output
—
Mercury 2.5 Preview
Input
$0.04
Output
$0.15
Where to run it

3 hosts

GPT-5 Nano2 hosts
HostInOutContextUptime
Azure AI Foundry$0.05 in·$0.40 out·400k·100% upOpenAI$0.05 in·$0.40 out·400k·97.4% 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
58%

Mercury 2.5 Preview uses 487.4x more bold

GPT-5 Nano
Mercury 2.5 Preview
60%Vocabulary65%
25wSentence Length14w
0.26Hedging0.44
0.0Bold4.9
4.4Lists3.3
0.00Emoji0.00
0.00Headings0.79
0.03Transitions0.20
Based on 20 + 26 text responses
Research

What we learned reading every model

FAQ

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Model pages

GPT-5 Nano logo
GPT-5 Nano59 outputs, specs and price
Mercury 2.5 Preview logo
Mercury 2.5 Preview58 outputs, specs and price
Rival
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Explore all of Rival

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