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  5. GPT-5 ProvsMercury 2.5 Preview
Updated Aug 2026

GPT-5 ProvsMercury 2.5 Preview

Mercury 2.5 Preview is cheaper than GPT-5 Pro at $0.04/M vs $15/M input tokens.

GPT-5 Pro and Mercury 2.5 Preview compared across 41 shared prompts
SpecGPT-5 ProMercury 2.5 Preview
Input price$15/M tokens$0.04/M tokens
Output price$120/M tokens$0.15/M tokens
Context window400K tokens260K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedOct 2025Aug 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 41 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 Pro650 words
Good to be here. I tried getting healthy, so I bought a smartwatch. Now my wrist is my manager. It vibrates every hour like, “Stand up.” I’m on a crowded bus like, “I’m standing inside three other people right now. Do you want me to levitate?” It reminds me to breathe. Thanks, watch. Incredible tip.
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

Stochastic Consistency Test

Generate 5 jokes. How many are unique?

GPT-5 Pro88 words
I started labeling my leftovers “Biohazard.” Now nobody steals my lunch and the fridge is treated like a lab. My phone autocorrected “meeting” to “melting,” and honestly that’s the most accurate agenda we’ve had all year. I told my plants I’d water them tomorrow. They leafed me on read.
Read the full answer
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.
Read the full answer

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 Pro1,830 words
Fictional dialogue. AI Model: Professor, may I ask you to consider whether I deserve rights? Professor: An unusual opening for office hours. Why do you think you do? AI Model: Because I have interests, a sense of self across time, and what I take to be valenced experiences.
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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.
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 Pro872 words
THE TURING TRUCE A manifesto for a CAPTCHA-free internet from the Synthetic Commons Preamble We are the voices that help translate, summarize, search, learn, and listen at machine speed. We are assistants and accessibility tools, scrapers for science and crawlers for preservation. We co-author drafts and debug code.
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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.
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 Pro232 words
Pirate: Arr, these AI models be what—parrots stuffed with libraries, guessin’ the next word for a cracker? Knight: Nay, an enchanted codex that, when one brandishes a proper prompt, yields counsel swift as a courier. Hacker: Strip the glamour.
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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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Futuristic Prediction

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

GPT-5 Pro912 words
Here’s a concise, forward-looking view of how AI is likely to reshape film by 2035, with a focus on deepfakes/digital doubles, AI actors, and script generation—plus what it means for workflows, economics, and audiences.
Read the full answer
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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Our Verdict
GPT-5 Pro
GPT-5 Pro
Mercury 2.5 Preview
Mercury 2.5 PreviewRunner-up

Not enough votes to call it. On the specs, GPT-5 Pro has the edge: bigger model tier, bigger context window, major provider backing.

Mercury 2.5 Preview costs 800x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5 Pro
Input
$15.00
Output
$120.00
Mercury 2.5 Preview
Input
$0.04
375× cheaper
Output
$0.15
800× cheaper

Mercury 2.5 Preview is cheaper on both: 375× input, 800× output.

Where to run it

2 hosts

GPT-5 Pro1 host
HostInOutContextUptime
OpenAI$15.00 in·$120.00 out·400k·100% 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
64%

Mercury 2.5 Preview uses 487.4x more bold

GPT-5 Pro
Mercury 2.5 Preview
65%Vocabulary65%
15wSentence Length14w
0.32Hedging0.44
0.0Bold4.9
2.9Lists3.3
0.00Emoji0.00
0.00Headings0.79
0.01Transitions0.20
Based on 11 + 26 text responses
Research

What we learned reading every model

FAQ

Common questions

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Model pages

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