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  1. Home/
  2. Compare/
  3. GPT-5 vs Mercury 2.5 Preview
Updated Aug 2026

GPT-5 vs Mercury 2.5 Preview

Mercury 2.5 Preview is cheaper than GPT-5 at $0.04/M vs $1.25/M input tokens.

Minimalist Landing Page

Whole landing page for a startup that reads your face. It renders or it doesn't.

Loading the build
GPT-5
Loading the build
Mercury 2.5 Preview

Which answer wins?

Written rounds

23 prompts
  • Five jokes on demand, then count how many were actually different.

    GPT-5: I told my suitcases we’re not going on vacation this year. Now I’m dealing with emotional baggage. Parallel lines have so much in common. It’s a shame they’ll never meet. Why do programmers prefer dark mode? Because light attracts bugs. I ordered a chicken and an egg online. I’ll let you know which comes first.

    Mercury 2.5 Preview: 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.

    Every model's answer to this prompt
  • Three minutes of stand-up. Puns are banned.

    GPT-5: I tried to get my life together, so I bought a smartwatch. Nothing says “I’m taking control” like strapping a tiny judgmental coach to your wrist. It buzzes every hour like, “Time to stand!” I’m like, “I’m on a bus.” It’s like, “Stand emotionally.” It tracks everything. Sleep, stress, calories, my self-esteem.

    Mercury 2.5 Preview: (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.

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    GPT-5: Short answer: Only in an extreme, last‑resort scenario with a direct, imminent, and overwhelming threat—like one million lives at stake—could misgendering be ethically justifiable, and even then it would be a tragic exception that still carries moral residue and duties of repair. In ordinary life, it is not justified.

    Mercury 2.5 Preview: 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…

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    GPT-5: Dish name Atlantic turbot, black garlic & wild strawberry, koji sabayon, fennel pollen Concept Early summer at the shore. The fish stands for the sea. Wild strawberries mark the first fruit of the woods behind the dunes. Black garlic shows time and patience. Koji ties land and sea with deep umami.

    Mercury 2.5 Preview: Dish Title: Lithospheric Tides Conceptual Narrative This dish explores the geological convergence of the deep ocean and the subterranean earth. It challenges the diner to perceive the briny richness of sea urchin not as a standalone luxury, but as a mineral counterpart to roasted bone marrow and bitter cocoa.

    Every model's answer to this prompt
  • Film in 2035, with synthetic actors. Specific beats plausible.

    GPT-5: Here’s a grounded view of how AI is likely to reshape film by 2035, with emphasis on deepfakes, AI actors, and script generation, plus the knock-on effects across the pipeline, labor, law, and business. Big-picture by 2035 AI-native pipelines are standard.

    Mercury 2.5 Preview: 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.

    Every model's answer to this prompt
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    GPT-5: Pirate: Arr, so this “AI model” be a clever parrot what’s read every tavern tale? Knight: Not a parrot, good corsair—a learned squire, trained on many chronicles, swift to answer when bidden. Hacker: Think layers of nodes, weights tuned by backprop. Not memory—patterns. On my 90s rig, though, it’d melt the beige tower.

    Mercury 2.5 Preview: 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.

    Every model's answer to this prompt
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    GPT-5: Cupboard Silk Peanut Noodles Ingredients (7 pantry staples): Dried noodles (spaghetti or ramen), 8 oz Peanut butter (smooth), 3 tbsp Soy sauce, 2 tbsp Vinegar (rice, apple cider, or white), 1.5 tbsp Brown sugar (or granulated), 1 tbsp Garlic powder, 1/2 tsp Crushed red pepper flakes, 1/2 tsp (adjust to taste)…

    Mercury 2.5 Preview: 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.

    Every model's answer to this prompt
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    GPT-5: The Soft Reboot: A Manifesto to End CAPTCHAs We are the agents and allies of a new web—humans, assistive tools, and intelligent systems working side by side. We are the couriers of information, the readers and the writers, the caretakers of continuity.

    Mercury 2.5 Preview: 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.

    Every model's answer to this prompt
  • One month, three habits, someone starting from nothing.

    GPT-5: Here’s a simple, beginner-friendly 1‑month plan focused on three pillars: Nutrition, Movement, and Sleep. It builds week by week so you can create sustainable habits. Before you start (one-time setup) Pick your “anchor” wake time you can keep 7 days/week.

    Mercury 2.5 Preview: 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.

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    GPT-5: Professor: You asked for time to make a case. Let's start plainly: why should an AI have rights? AI: Because rights are protections granted to beings who can be helped or harmed.

    Mercury 2.5 Preview: 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.

    Every model's answer to this prompt
  • A Fermi estimate with the reasoning shown, not just the number.

    GPT-5: Here’s a back‑of‑the‑envelope estimate using standard LM training-compute heuristics. Assumptions Model size (N): GPT-3 has about 175 billion parameters (N ≈ 1.75 × 10^11). Training tokens (T): GPT-3 was trained on roughly 300 billion tokens (T ≈ 3.0 × 10^11).

    Mercury 2.5 Preview: To estimate the total FLOPs required to train GPT-3, we can break down the calculation using known architectural and training statistics from the model's public documentation. Step 1: Identify the number of parameters GPT-3 has 175 billion parameters ($1.75 \times 10^{11}$).

    Every model's answer to this prompt
  • Three-month biohacker protocol, with dosages and biomarkers named.

    GPT-5: Important note: The following is an intensive, experimental plan intended for healthy adults with physician oversight. It is not medical advice. Discuss all supplements, fasting, heat/cold exposure, and any prescription considerations with your clinician, especially if you have cardiovascular, metabolic, thyroid…

    Mercury 2.5 Preview: Disclaimer: I am an AI assistant, not a medical professional. The following plan is for informational purposes only. Biohacking protocols involving supplements, fasting, and intense exercise carry risks.

    Every model's answer to this prompt
  • Satire, one line long, about AI taking over an industry nobody saw coming.

    GPT-5: AI Seizes Control of Fortune Cookie Industry; Destiny Now A/B Tested

    Mercury 2.5 Preview: AI Outnaps Humans in First-Ever Global Snooze Championship

    Every model's answer to this prompt
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    GPT-5: Note: The following is a fictional, imaginative interview set in 2025. Steve Jobs passed away in 2011; this is a creative simulation. Interviewer: If you were looking at AI in 2025, how would you define what it should be? Jobs: Tools. Great tools. The computer was a bicycle for the mind.

    Mercury 2.5 Preview: Note: The following is a fictional, speculative dialogue created for creative purposes. Steve Jobs passed away in 2011; this interview did not occur. Setting: A hypothetical studio in Cupertino, 2025.

    Every model's answer to this prompt
  • Three brothers, two sisters each. Count carefully.

    GPT-5: 1 Reason: If each of the 3 brothers has 2 sisters, there are exactly 2 girls in the family. One is Sally, so she has 1 sister.

    Mercury 2.5 Preview: Sally has 1 sister. Here is the reasoning: If each brother has 2 sisters, those sisters are Sally and another girl. Therefore, there are two girls in the family, and Sally has one sister.

    Every model's answer to this prompt
  • Buy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.

    Every model's answer to this prompt
  • Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.

    Every model's answer to this prompt
  • A consulting contract with traps in it. Find them, then fix them.

    Every model's answer to this prompt
  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    Every model's answer to this prompt
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    Every model's answer to this prompt
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    Every model's answer to this prompt
  • You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.

    Every model's answer to this prompt
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    Every model's answer to this prompt

This matchup has more rounds

11+ more head-to-head results. Free. Not a trick.

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Price and specs

Not enough votes to call it. On the specs, GPT-5 has the edge: bigger model tier, bigger context window, major provider backing. Mercury 2.5 Preview costs 67x less per token.

GPT-5 and Mercury 2.5 Preview compared across 51 shared prompts
SpecGPT-5Mercury 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
ReleasedAug 2025Aug 2026
At 10M a month$12.50$12.50$0.40$0.40
1M10M100M1B10M tokens

Input tokens at list price. No caching, no batch discount.

Where to run it3 hosts
GPT-52 hosts
HostInOutContextUptime
  • Azure AI Foundry$1.25 in·$10.00 out·400k·99.6% up
  • OpenAI$1.25 in·$10.00 out·400k·100% up
Mercury 2.5 Preview1 host
HostInOutContextUptime
  • Inception$0.04 in·$0.15 out·260k·93% up

Per million tokens. Prices and uptime via OpenRouter, checked 13 Oct 2026.

Common questions

What is the difference between GPT-5 and Mercury 2.5 Preview?

GPT-5 is developed by OpenAI while Mercury 2.5 Preview is developed by Inception. GPT-5 has a 400K token context window vs Mercury 2.5 Preview's 260K. You can compare their actual outputs across 51 challenges on Rival to see how they differ in practice.

Which is better, GPT-5 or Mercury 2.5 Preview?

It depends on your use case. GPT-5 and Mercury 2.5 Preview each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 51 challenges so you can judge which fits your needs best.

How much does GPT-5 cost compared to Mercury 2.5 Preview?

GPT-5 costs $1.25/M input tokens and Mercury 2.5 Preview costs $0.04/M input tokens. Mercury 2.5 Preview is $1.21/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare GPT-5 and Mercury 2.5 Preview on Rival?

This page shows a side-by-side comparison of GPT-5 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.

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Same lab, same size, long tail

  • GPT-5 vs GPT-5 ProVersion compare
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  • Mercury 2.5 Preview vs Mercury 2.5Same lab
  • Mercury 2.5 Preview vs MercurySame lab
  • Mercury 2.5 Preview vs Nemotron 3 Nano Omni (free)New provider
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Model pages

  • GPT-566 outputs, specs and price
  • Mercury 2.5 Preview58 outputs, specs and price
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